Complaining about the joysticks, bah... c'mon, most PC gamers still used to use their crappy keyboards for controlling platformers 20 years later!

1. DMA sprites, but they are basically only start-stop and has no "new pointer". So for animations you need to copy new data over the old.
2. Copper has two different sources of control input, but can only act on one at a time (screen position and blitter done).
3. Blitter needs separate mask data, and either one blit per bitplane or N times mask size for N bitplanes. I could see a kind of loop mode for one of the blitter channels where it wouldn't add the modulo but reset the internal pointer N times.
4. The custom chip address space was not laid out with space for 256 colours. They could simply have said "reserved for colours" or something.
5. You can't wrap the screen around horizontally (i.e. a pointer change midway on each raster line). I would have though they might have wanted it for stuff similar to Defender.
6. The copper has no repeat/fill/burst mode. Instead of address+value word pairs I would have expected them to get tired of seeing copperlists that only set up new colours incrementally up the address range. With plenty of unused bits in the copper addressing format I would think you could do "from $address to address+N: write the following words". (N being small enough to fit inside 16 bits together with address.)

I actually love the SID sound... a PSG is a cheap way to produce sound without wasting ram. But let's say instead of a SID you had an AY-3-8910 ... this coupled with the 4 PCM channels from Paula, you could have all 4 channels playing music while the other 3 for SFX or you could mix them, like 2 PCM + 3 PSG for music and 2 PCM for SFX or 3 PCM + 2 PSG for music and 1 PCM + 2 PSG for SFX....

At least we wouldn't have any reason to suffer the "Music or SFX" syndrome so many Amiga games have.

The only thing that annoyed me at the time was the clicking disk drives.

Yes, that's why I put it as number 1 mistake, bigger than the MIDI. Even today in some Amiga games I feel.... limited.... disabled.... hopeless.... Why I can't easily choose weapon, jump over ladders and make semi turns, like in a normal game!?

It is annoying, but again, not a limitation of the Amiga design.

Thinking about the original A1000, I don't see many things that could have realistically been done significantly better (hardware wise). Perhaps the ability to have at least some Fast RAM installed directly on the motherboard. It would have taken space on the board, but external RAM expansions are just horrible (especially with a system that is already fairly large).

1. Better than putting shitty BASIC in the ROM for some usability without disk. Remember in 1985 disk space was already huge by the time - 10 MB HD for under $1000 and 800 KB on floppy. The ROM was meant for basic stuff (hence the name BIOS on PC).
2. RAM was expensive - the original Amiga 1000 came with 256 KB RAM (and 256 KB on front cartridge). 320x240 chunky mode means 75 KB for the graphics alone (more than the total RAM of C64 and most of the computers at the time. So you had 256-75 KB = 181 KB without the OS etc. With the OS the user would had available less than 128 KB - less than the 8 bit machines at the time - Commodore 128 and Apple IIc.
3. Big fault - the chips for implementing this + the connectors costed less than 10$.
4. I was thinking about this - by using 65816 or even pushing MOS to create even faster 6502 derivative, they could made the machine backwards compatible with the C64, VIC, PET etc.. just like the Apple IIGS is backwards compatible with the Apple IIs... but........ 65816 is very slow. They Apple IIGS is almost useless without accelerator card (ZIP card), but on the other hand, nobody was going to buy the Commodore 64 anymore, when the Amiga can play all the software + better. But in 1985 the 680x0 were the best processors available. Even Intel was struggling to beat Motorola dominance in the CPU market. Most of the 16-bit machines of the era, including computers, printers, faxes, ballistic missiles control heads, etc used 680x0 CPUs.
5. By 1985 view, the OS is quite okay - reference - MacOS, Windows, GEOS, QLDos of the time (ugly as ... black and white TV).
6. Yes, faster copper could have compensated for the HAM and even allowing HAM alike modes with fast transfer of data with faster scanline colour switches by the blitter etc.., i.e. HAM that's usable in games and animations.
7. Multi button joystick shall have been released from day one. Even if using custom port for it - remember this was new machine, so everything was new. The manufacturers would have started making 3 button pads, the games supporting them. Nobody was going to be cheap for 20$ Joystick when they spent 1285$ on the machine alone.

One very irritating design mistake is the total stereo separation. Sure, the Amiga has four stereo voices, but no real way to make use of a stereo setup because any single sound channel is either on full blast on the left or on the right.

Even basic panning capability inside or outside Paula shouldn't have been difficult to do — Atari did it using a simple off-the-shelf chip in the STe.

I agree, and they never upgraded anything in sound from earliest up to the latest models. All the same.

One more thing comes to mind:

No multitasking in Workbench!

Amiga got this great preemptive multitasking OS, but the Workbench makes poor usage of this - there should have been no "Zzzz", but a progress window for disk activities.

Nothing it didn't get right imo, tbh we were so lucky the Amiga ever launched at all is enough to not look back in hindsight and wish we had something better about it, every machine has its flaws, the Amiga ruled back then and we enjoyed using it and didn't moan about it then like we seem to now!

Floppies and multitasking is an oxymoron. Even late 2000s PC freeze when you do floppies stuff. There is joke about this.

Bill Gates' son asks his father:
"Dad, what's multitasking?"
"Let me finish formatting this floppy and I will tell you."

Works fine on Scalos.
Or XCopy in the background... You just need a HD or enough floppy-drives.

This was one of the cool Amiga-features: using DMA for the floppy, so it does not slow down the whole computer as it did on PC
... well Windows has problems with disk activities until today (DMA or not). Just SSDs are hiding the problem now.

But a 1985 Amiga doesn't. It's just Workbench. And the same problem applies if you have a hard drive.

Were those packs of disk you bought high density ones?

Because the "data density" written by the Amiga disk controller is more or less the same as for double-desnity PC/720KB disks. The extra capacity comes from not needing gaps between sectors since the Amiga reads/writes the whole track at once.

I am also a little bit confused on this point.
Sure there were sometimes bad disks and crashes. And there was disk-doctor and disk-salvage... but this was a OFS/FFS problem.
And in most cases formatting a disk (twice) solved everything..

I never had to bring a pack of disk back to the shop.

It would be really interesting to hear any hindsights on this from the original Amiga HW and SW engineers.

Usually high density disks worked better on Amiga. For example Verbatim DataLife floppies worked best, but they still gave errors after 10-20 writes, even if they had lifetime warranty. Same for 3M floppies. An engineer at one of the shops explained to me the Amiga writing mechanism for floppies is less robust than the PC's one, hence the more frequent errors. Additionally the Amiga floppies had problems because of the multitasking - i.e. writing 2 files at once will make the head spin around like mad. Then the Amiga custom format floppies prevented the Amiga adapting the HD floppy format, that was available since 1986. Even in late 1995 games were coming on DD floppies. Amiga adventure games were coming on many floppies, which costed software houses more money - i.e. Beneath a Steel Sky on 15 disks (Instead of 8), Monkey Island on 11 disks (instead of 6) etc. etc..

Most of that doesn't sound very factual, and certainly doesn't match my experiences.

Any Amiga can use HD floppies (formatted to 1760kB) if you have a high-density drive, but only the A4000 came with one. This is another thing where the market chose the lowest common denominator, not a technical limitation. Just like with the joysticks.

I don't think the Amiga got the floppy decision wrong at all, it could have picked worse as in the 3" disk or 5.25" disk or even use a worse drive like the Atari ST only reading single sided disk of 360k!
Sure it was out of date by the time the A1200 hit, but we aren't talking about 1992, its 1984/5, DD disks were easily enough.