They have at least one color camera that "is like a consumer point and shoot" on the mast. The pictures released are from the very technically-limited hazard cams, which are really only for the drivers to see what they have to deal with.

Within a week we should see some full-color images coming in.

There is a color camera on it. It's just not deployed yet.

https://twitter.com/MarsCuriosity/status/232412416728788992

As I understand they do, but even if you had it been deployed seconds after it touched down, the wait for returning images would have been a while. Packet radio from that distance is no joke.

From Earth I'd rather have a few crappy thumbnails to confirm that the vehicle wasn't upside down or something in a few minutes than something National Geographic worthy in a few days.