I only see (from experience) carrying without one in the pipe when using a holster that doesn't quite have the security you'd like. When I first started carrying (and sometimes now) I did not chamber a round when carrying in my bellyband due to the thinness of the material protecting the trigger guard (and lack of manual safety). I always carry +1 otherwise, but when ultimate concealment is needed there are tradeoffs in security.
For example, I would never carry +1 in a "smart" carry holster.
I did for a year never had a second thought about it