There's no way I'd ever feel comfortable on a brakeless bike, particularly not in traffic.
There are just too many ways for it to go wrong. Cycling can be dangerous as it is, especially when commuting, so I can't imagine taking brakes out of the mix on top of that.
Obviously there must be some upside if people are willing to do it but I just can't see it.
It seems a bit irresponsible as well, to knowingly commute in traffic with no brakes. At that point you're not just endangering yourself but possibly anyone else you're on the road with. What if you can't stop in time and a driver swerves to avoid you and ends up wrecking?
It just doesn't seem smart.