Am I the only one who actually likes brown games? Brown games (Gears Of War, Fallout 1,2,3 (2D Fallouts were brown too!)) are much better looking than gray (Quake 1/2, Half-Life) games and magnitudes better than coloured nonsense (Uncharted 2 (oh god, it hurts my eyes!), Ratchet and Clank etc)!
Let it be more brown games! Personally I'd restrict game developers to use only murky colours and corresponding lighting! Oh, and obligatory pixel shading to wash out everything into single bland scene.
And I'm dead serious here - this stuff is really awesome! There are more to it than designers' tastes, of course - Gears Of War-like shading allows to hide lighting imperfections and use fewer textures (and not that high-res at that).
The second reason is that brown games aren't just brown - they are brown and dark and washed out because of their setting - such colour palette is perfect for post-nuclear or just plain dark/noir shooters (It's hard to argue that such games became very popular this generation).
I like post-nuclear setting, I like washed out palette and dim lighting, and I'm just happy that many games are like that these days. They won't be like that forever - remember Quake 1/2 age, when every shooter (and even some RPGs like Anachronox) had been trying to look like id's gray-green blockbusters. Have you seen something green and gray lately?