4 good reasons to holster
Personally i like IWB at 9:00 (i'm a lefty) but whether you like IWB, OWB, shoulder rig, or even fannypack, the last thing in the world i'd do is shove a gun in my pocket - unless it was a LCP/R with a pocket holster made specifically for the gun. I have 4 main reasons.
1. Safety. Mine. Covering the trigger completely is simply safer than not;, regardless of how you feel about your particular gun or its trigger, it can't get snagged if it's covered. The point is, i carry in order to defend myself, not to place myself in some kind of controlled jeopardy. Many holsters go a little farther and allow you to secure the hammer for added safety - an overlooked by important feature. I want to eliminate the slightest risk i'll have a ND and shoot myself, or worse - someone i care about - without even handling the damn gun.
2. Reliability. A holster keeps pocket lint out of the barrel, action, slide, and magazine. It keeps sweat and salt off the metal surfaces, and it keeps the gun dry for a better grip. If you ever need it, you'll need it more than anything else, ever. Why wouldn't you want to take every step to ensure it is clean and fully functional when the SHTF?
3. Retention/Consistency. In the holster, the gun is always where you put it last. (If your holster moves around, replace it). No slipping off your belt in the checkout line and clattering onto the floor. No dropping into the toilet bowl accidentally when you go to drop a deuce, as one of the poster's put it so quaintly. No winding up in the small of your back when you started it at your kidney. No diving down to the bottom of a deep pocket, making the clothes hang all wrong and pinching the pocket opening.
4. Reloads. Most holsters have (or are compatible with, anyway) pouches for extra mags or speedloaders. No telling if you'll ever need them, but that feeble argument also applies to the gun itself, doesn't it? OK, now that you've loaded your pockets with guns and mags, where do you put your money and cigarette lighter? your wallet? Your car keys? Your pocketknife?
So, whatever. carry how you like. But when your pants are flopping around like multiple pendulums and you obviously have significant heavy objects flopping around in your pockets, i'll still be covert. and i know my gun will fire.