Although,I'm not positive about this, I think one of the criticism's about the A1200,(Apart from the standard one's of the same sound chip as the A500 etc.),was in fact to do with the memory allocation too.
It might've been to do with 3D games in particular, but if memory serves,I believe the argument was that the A1200's processing was much improved with the addition of as little as a 1/2 meg Fast Ram add-on rather than just the standard 2Meg Chip ram.
I always thought it was ironic as the common complaint for 1meg games on the older OCS/ECS a500/600 came from getting the games to run on both the older A500 with 512kChip & 512k fast ram & the ECS machines that came with 1meg chip ram as standard!!
I sure there are coders out there who'll have a better understanding of why though,I just recall that it was an issue, aat least for 3D AGA games,not to mention the lack of a Byte-per pixel mode ala like the PC's of the time.