I use a hose on gentle spray to hose down the mountainbike. A little Simple Green when I'm feeling ambitious.
The road bike (neked ti) and the commuter (painted aluminum) get occasional wipedowns with Fantastik wipes.

I don't think lack of cleaning on the frame is an issue - depending on the material - except to wreck the paint perhaps. (Rust could become a problem on steel frames) Lack of cleaning the chain and drivetrain, of course, can lead to all sorts of problems.