While Chaos Gate was exciting because it was "like" 40K X-COM it lacked a lot of the depth of X-Com and was poorly executed. There was no strategic level where you built a base of operations, researched, trained, shot down alien craft, etc. Tactically the marines really never gained abilities as far as I remember, you simply unlocked new squads so it was hard to garner the same attachment to individual marines that you can in X-Com.
The game itself was full of bugs. I remember many graphical glitches which caused the screen to wig out and sometimes crash the entire game. There were also bugs which would corrupt save game files.
On the original topic... I second the having a 40k style X-Com game. I think Bioware could do Warhammer Fantasy justice while Bethesda handles 40k. I would love to see another epic game. My preference is for turn based like the old Final Liberation, but, I'd take whatever I could get. Lastly, for a first-person perspective game I'd like to see Irrational Games (Necromunda maybe?).