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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.)
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