I see your point. However, I ride in crap traction conditions many times per year, where I'm very glad to have a rear brake; but I have yet to have a brake fail. It's definitely nice to have the insurance of a backup, but being able to brake where traction is poor is much more important to me on a day to day basis. So I think it's a more persuasive argument for having a brake on both wheel. That's all I was trying to say.

this.