It's been like that since the first time we saw it, they've explained why they made it like that and they're not going to change it with less than four months till release.
Yeah, I know, and I... I don't care
I do not like the changes, and I don't agree with their conclusions regarding the animation of the creature.
Oh, and, four months? That's about three months more time then it would take to change the legs, and two months more than needed to redo animations.
Also, it was never an issue in AVP 99 or AVP 2 to get the aliens to animate smooth and run fast with biped legs. Never once had I heard anyone remark on the Aliens in 99 being "goofy" when they tore down a haul and ate a marines face off their face.