I know a temp gauge is not the answer but it sure brings a lot of dark questions into the light, especially for dummys. For example; If your top temp reads 280 chances are you're running super rich. If you're reading 450 or better it's a sign that you have an air leak and/or are under jetted. To the average mopedist a proper plug chop is much more complicated and less assuring than reading a temp in realtime.
Temp gauge or not, you still have to tune. It's not a substitute to tuning but rather an informative aid telling you that something's wrong (or that it's right for that matter).
I think a temp gauge is the best 40 bucks spent on any tuned build.