People are expecting too much from a game that still uses DX9 in 2013 :P
Imho Aion looks a bit worse than ARR but far worse than the current FFXIV. Aion is just more colorful (lots of purple lol).
If you want a game with really nice surroundings you should look at The Secret World. But it lacks character details.
The massive detail is what's making the current FFXIV sluggish for some people... well and the huge lag. The game doesn't scale down detail over distance, instead the stuff just disapears. If the game showed all players in range in Uldah you wouldn't even be able to move. SE needs to create an engine that can scale details depending on the situation. A scene with 10 characters can't be rendered the same way as a scene with 1000 characters, unless everyone looks derp
>.<