For those who are against it, maybe some experimentation is in order with the guns youre uncomfortable with. You do have to at least prove it to yourself, and not just take others thoughts on it. I say thoughts, because so much seems to be just that. I havent heard of anyone speaking from "experience" as to the guns going off because they werent using a holster.
I was always told you cant carry a Glock in this fashion, but so far, with pretty much a year or more of daily use with a couple of spare "unloaded" Glocks, just thrust into my waistband or pockets, I have yet to find the trigger dropped, unless the trigger has been intentionally pulled. All the scary stuff I was told will happen has yet to. At this point, Im not concerned about sticking a loaded upholstered Glock in my waistband.
Now going in the other direction, my buddy found out that carrying a Baby Browning loaded and kept behind a hanky in his back pocket wasnt a good idea. He was working in the garden, bent over, and the gun went off. Lucky for him, all it did was blow a hole in his jeans. He no longer carries that way, nor does he carry the Browning, and switched to a TCP.
A little prior practice, thought, and common sense can go a long way in eliminating problems, and some of the fear.