I enjoy my computer - it helps me set and gain my goals.
I.e., I had a goal today of a 30 mile ride - and I hit it perfectly.
I will set a goal of 35 miles on my next significant ride, and I will know when I am there.
I don't happen to give a hoot about my average speed, but I do enjoy knowing my top speed.
But, tape yours over if you like. The wonderful thing about bicycling is that we can all enjoy it in different ways with different emphases.