Originally Posted by derath
Or people who simply like using the tops as another hand position, yet are concerned about having to react quickly and switch to the hoods in a braking situation.
If you aren't a WW or racing, I see no downside to having them.
-D
Downside is that your center of gravity is very high when your hands are on the top of the bar, so braking hard can cause a face plant (aka kissing concrete).
This isn't a problem for cyclocross racers, since they train for those situations and are generally going uphill when their hands are on the bars, which makes a face plant much more difficult.