Indeed, AGA could have been much better.
With the same memory bandwidth they could have included a blitter running at 4x speed (though it would have to fetch 64 pixels per go). Or allowed the processor to access chipmemory at twice the speed.
And don't get me started on AGA sprites. While 8x64 pixels@3 colours/4x64 pixels @15 colours was rather nice, they could have (again, in the same memory bandwidth) also given us 16/8x32 pixels or 32/16x16 pixel sprites. Which would have been much more useful for games.
Same with the sprite colours, they could've allowed a 16 colour pallete per sprite pair.
All things that could've been done using the same 1992 level technology they had.
Ah well, no sense in ranting over it I suppose - perhaps I should just be happy we got an upgrade to AGA at all. It's still better than nothing.