I used to have a top tube pad because one of my brake cable holders was broken and sharp but now its been fixed and the pad hit the road. I didn't want to cut myself on the balls.

I think most people have them because they like the style. If you are the type of person who is going to match your frame, bar tape, wheels, etc adding a matching top tube pad probably seems like a good idea. Lets not forget that outside of the critical eye of this forum that some people might actually think your top tube pad is cool.

Maybe they protect your balls when your doing over exaggerated 30 foot skids up to the local coffee shop? Maybe the protect your new cool dude paint job? Maybe they match your messenger bag? Who knows.