They couldn't get official CD keys from THQ to allow user registration on NovaWorld. That is still a hurdle with the Steam version so someone else tells me. Plus the NW lobbies are down 1/2 the time.
I have no idea what the goal for THQ is. I was surprised, but happy they included all the lobby fixes, as well as my own lobby DLL into their official build. They are allowed to release it on any provider now, including Steam. I hope THQ reaches out direct at some point as I'd love to work with directly