I heartliy see and sccept your point. I do.
The thing is though that really couldnt the same be said for any content for this game? I mean afterall is said and done, its 2009 now (!) and really there's an engine out there for every possible theme for an fps possible!
You know - I mean if you wanted to make The Doom 3 engine behave like traditional quake it can be done - just disable crouch, increase the movement speed of the player, make touchable buttons, tweak the controls so you can jump and strafe at the same time and never take more than 5% falling damage, and hey presto!
Infact there IS a Doom engine Quake mod, which tried to emulate the Quake game....
http://www.doomwadstation.com/doom3tc/quakemod/
So i mean...... ?