On a track you won't really need to brake and shouldn't and on the road with cars, pedestrians, light changes and various other forms of complete unpredictability having an actual brake could save you and your life someday. Plus you can run nicer tires that give you a better ride quality and won't run through them so much. You can get some really lightweight stuff and some really nice stuff braking wise and on a drop bar you can have a place to put your hands which is handy.

I feel like I haven't said it in a while but if you don't skid your undies why would you skid you bike?