<SNIP> as it's a deathtrap without one.
Not that old chesnut.
I suppose you tell everyone to ride with a helmet on too, do you?
Brakes on fixies are a personal thing.
Personally I ride my fixie (when I do ride it) with a front brake only. Not exactly, strictly speaking, street legal, but it is my choice.
As long as you are able to make an informed choice that is influenced more by your a) willingness to break the law AND b) the knowledge that you can stop the bike with no front brake in an emergency and not by hipster fashion, then go ahead.
Actually a fixie with a front brake only IS legal.
However, the problem is that a rear-only braked bike has approx double the stopping distance, as the harder the brake works, the more weight is pitched onto the front wheel, so lessening the rear's grip. Bicycling Science has a lengthy analysis if you want to dig into it.
Ride it or milk it!