I try to always return the plate to the tripod when that camera goes off for more than a couple of shots. Why?
First, I have multiple bodies. And I've had some early morning shoots (as in: leave the house at 4am). I want my equipment ready to go. Which is why after I've finished shooting, I return the camera mode to "A" (aperture), ISO to 100, and WB to "auto". I replace any battery that is less than half a charge left when I'm done. I don't want to pick the camera (or gear) up the next day and realize "oh crap, my battery is near empty" or "F*ck it, my tripod faceplate is on the other body!"
Second, on shoots where I'm using a tripod outdoors I often have need of that bottom of the camera. I may be screwing in a gorillapod or a platypod (because they provide something the tripod doesn't). Or I'm swapping out lens and still need to keep the camera on the tripod (for instance, I shoot closeups of the Bald Eagle with my 600mm and then switch to my 85mm for a landscape shot and both need to use the same plate). And I have a Black Rapid sling (that screws in to the bottom of my camera).
I think the key thing here is not that I'm right (or the others are right). It's to be consistent. Otherwise sometimes you take it off and attach it to the tripod. Or take it off and put it in a pocket. Or leave it on the camera body. And then you're scrambling looking for it.