HT said at some point something like "there hadn't been anything interesting in graphics development until pixel shaders, with those we can do some interesting stuff", in the sense that it wasn't feasible to overhaul the 3D engine untill then, in his opinion, if I remember his saying so correctly.
imo HTC does wtf they want, it's their game. That means responding to players' and their own demands, and developing whatever they want for whatever end result they want.
So far I'm satisfied and deem it worth paying to play it.
It's a bit strange to see the AH2 graphics so little ahead of AH1's, but my impression is it's no big deal, as AH is more about gameplay, and it doesn't look like this is anything but just the beginning of exploiting the new engine, Beta or not.