I've said it before and say it again, it's absolutely possible to create a scalable graphics engine, thus neither neglecting the low end nor the high end systems out there.
Better lighting will go a long way, but I'd also like to see bump mapping and volumetric fog/clouds/smoke to be added.
Not wanting to be disrespectful or anything, but I have the distinct feeling that HTC isn't exactly hard at work on AH. There are other online games with a lower monthly fee than AH that update and improve (not bug fixes) their games far more frequently.
I'll be happy to be proven wrong with the release of 1.11, which, when/if it happens, should be a major improvement for the 4 months+ it has been in the works. But, let me be frank here, better lightning, 3 new planes and larger towns are at best a minor improvement. The mission arena may have been a major improvement but that has been postponed until 1.12.
-Amboss