I've been trying hard to increase my cadence, so the computer set to show the cadence is (for me, at least) necessary.

I'm also a wee bit obsessive/compulsive so knowing how far/fast I've gone fills a psychological need. Also, since I post on bike journal, those numbers come in handy.

My computer also continuously shows MPH, but I don't worry about it much, I'm slow. I know it. I don't worry about it any more. I still like to know HOW slow, though. Go figure.