The Dreamcast is one unified platform.. Amiga OTOH is spread very thin across a whole crapload of different configurations, resulting in very varying performance. And even the OS was branched off into 68k Classic, Morph OS, OS4 PPC, AROS etc..
So no wonder that any given config is going to have precious few followers.
Im really surprised to see / hear ppl only now getting some expansion for their 1200s.. I mean, if you haven't got that 030 or better by now.. The machine is 23 years old...
So if you were an indie developer, what would you target? Ok, lets go for 68k Classic OS. Next choice: Minimum CPU requirement? Minimum RAM? RTG only or AGA?
Whatever you choose you'll be faced with more than one dilemma..
And the kind of games we played on the Amiga in the late 80s, early 90s.. Those kind of ghames are mass produced for smartphones and given away for "free" (AdWare) ...
If you have a decent PC or Mac, you can use tools such as Unity and put together a decent game very quickly.
Amiga has -by modern standards- very little in the way of Dev -friendly tools that would make your life easy.. And even if they were, the results would probably not be very impressive.. because the most impressive stuff was always done in 68k asm. ;-)
A year or so ago, there was a campaign for the AmiDark engine (which I supported at the time) but the campaign failed, and it got me thinking... How come that there are so many ppl out there that still wanna pay £300-500 for 20 year old Blizzard cards, £100 for a single 060 chip, etc.. but when it comes to supporting software.. nope...
So its no wonder we end up with expensive retro rigs but never play anything other than the 20 year old stuff.