There was a BF 1942 Mod fo StarWars, and it was played well.
Many Players make the switch to BF2 and they like it - were is much more teamplay in BF2 than in UT2004 (i play both, and i like UT for Deathmatch).

It's a community thing.
The BF Community likes the BF-Style of combat, the UT communty likes the UT Style of combat.
Not many UT Players will download a Mod and play it, if this mod is to far from the typical UT Style of Combat.

FirstStrike was first a BF2 Mod, and was later changed to BF2142, sadly many BF2 Players don't have buyed BF 2142 because (OrginalQuotes):
1.) "They think it's a mod and EA hasn't the right to take money for a mod" (so as modding is no work, and the coders from DICE work for free )
2.) "They don't like SciFi Szenarios with Lasers and Starships" (Sorry, no Lasers and Starships in BF 2142 - but in FirstStrike)
3.) "They don't like the totally differnet gameplay" (They would be shocked it the try Onslaught in UT 2004)

I have heard from many BF2 Players they would give First Strike a try if it was for BF2 - but they never ever will buy BF 2142.
Because -for those Players- FirstStrike isn't worth the 40 €uros they have to pay to buy BF 2142. 
( And i don't think they won't pay 10 €uros for UT 2004 either)

CYNIC, n. A blackguard whose faulty vision sees things as they are, not as they ought to be. Hence the custom among the Scythians of plucking out a cynic’s eyes to improve his vision

alreech summed it up quite well, if i were a dev, i would just say:

"whatever alreech said"

NO, i cant agree to that (thats what i meant by "genre")