Ah, ok, I looked at schematics. I basically forgot about DRAM...Agnus had to do the DRAM address translation (+refresh). That does explain it...Still, I think it's a bad compromise. I think it would have been worth it to add DRAM support to eg Gary in order to have cheap fastram...
But of course, that's in hindsight. Maybe Commodore thought cheap fastram sideport expansions would flouris?
Not exactly.

As Bloodline said, they had more important thing to care of.
Six months after A1000 debut, CBM was grasping to ensure liquid business since some massive loans were due settling. A massive fraction of revenue came from still actual 8-bit market, while A1000 sales were pretty discouraging, nowhere near the Atari competition. New CEO, Rattigan, cut the costs of perex and opex by splitting platform into 2 separate streamlines. Simpler and cheaper A500 was aimed at market penetration currenttly owned by C64 and A2000 shoot for performance/productivity line claimed by Atari. It would be nice to find some figures how much CBM saved on those A1000vsA500 and A1000vsA2000 ratios, but somehow it worked since just before launch of A500/2000 CBM reported profit.
Considering all issues of that specific time, I think that CBM might have done more damage after A1000 debut. They had second chance (1st goes to original Amiga team) with Rattigan, but greedy Gould fired him in split second. Not to mention the awful CBM marketing which blew every damn chance to expand userbase and increase organic market share.
IMHO, when we're discoussing what might been wise to do back then, I'll say that CBM might saved it's ass if they went IBM route. Licence chipset, open platform for 3rd party HW assemby and then apply more focus on SW development which would generate enough momentum of detailed concepts and ideas needing better HW. Unfortunatelly, when told about IBM route, those idiots understood only COMPATIBILITY.
Ahh...:furious: