The only ones other than FW that I really experience it on are Condemned, like you say, and Anchor 9. I've probably had it occasionally on other maps at really high action moments, but nothing that jumps to mind like those 2. Also, Asylum has it really bad. Even slight action anywhere around Sniper building triggers it, looking along from Sniper to Sniper triggers it, scoping in from the Base flats towards the enemy Sniper (basically looking at/past Car) triggers it. Squad Slayer and the increased action that 5v5 brings has really brought home just how bad Asylum is for framerate drops. And I agree, this is an issue embedded in the poorly designed FW canvas/pieces and, to an extent, the Reach engine itself which is clearly putting too much demand on the hardware at times, rather than forgers being unreasonably frivolous when building. However, in purely practical terms you can't fault Bungie for trying to provide the best MM experience based on what we have right now. Sure they should have designed FW/the game better, but based on the fact that they have to work with what we have now in terms of selecting forge maps for MM, and the fact that any patch options are out of their hands right now, they're doing the right thing. I'd rather have a better MM experience than a crappy one just so they can avoid being hypocritical.
Rage at them in the Optimatch forums on the B.net. It always works as long as you have a long wall of text.