I guess what it comes down to is that old argument of art style vs
technology. Personally, I'm a fan of the art style of WoW, but I'm
also of the opinion that eventually you have to upgrade the graphics
form a technological standpoint, because the game will look so
horribly dated in time that even games with lesser art direction will
look better. And I believe that's the case with WoW now. It doesn't
need to compete with Aion, but to drag back the GW reference, even if
it was on par with Guild Wars 1 while retaining the same art style, it
would be enough to breathe some life into the game and make it last
alongside GW2 and Aion in the future, (and/or until Blizzard's "next
gen" MMO comes out).

I admit graphics aren't, and shouldn't be, the main draw of a game,
but when one of the most common complaints I hear about Warcraft when
I try to get other (gw players) to play with me is that they're unable
to justify paying monthly for a game which has such dated graphics and
virtually non-existent character customization. Though the bashing is
usually not on the race models themselves, but mostly on the lack of
detail on the armors, along with the inability to dye it different
colors to have some semblance of a matching set