THe biggest issue I see, goes with a general philosophy.
Once you commit to something , stick with it !
It would be silly to make some kind of decision about changing game engines before the project is seen through to its completion.
Especially in our current state where we are trying to get as many players as possible, to even contemplate changing gears mid-flight would be a total waste of the developers time... and we know theres barely enough time to get what needs to be done here completed.
If they were making big money doing this I could see changing directions if a sizeable benefit was to be had... I dont see a sizeable benefit in changing engines from 2142 to something else.
Keep on moving forward, and make this game better than 2142 could ever be ... then you have done something notable !

"The victorious win the battle, then go out to fight ... while the defeated go out to fight, then try to win the battle.   -SunTzu
"The only difference between a capitalist and a communist is that the communist hates competition!" -Circuit

@Luke Skyraper: Exactly. Everything to this point has been done on 2142 - why change now? The models might be transferable, but most of the coding would have to be redone to fit the different engine. Obviously, all the current players own 2142 - and, almost as obviously, not all of them own UT. So you'd have to start over, rebuilding both the mod itself as well as the community, for minimal, if any, benefit.

Now, I can't speak so loudly for why 2142 was chosen originally, nor do I need to - that's been covered already.

@yultemsee: I don't believe it has native support for squads, although from what I've heard about the modding engine it might be possible to add. There's a good reason why 2142 was chosen - it had native coding for walkers, squads, large battlefields, etc.