Do holsters absolutely need retention straps?
Mine does...I carry a 642 OWB and I prefer the pouch to be form fitted but not tight...it will never pass the "upside-down n shake" test.....so I use a retention strap...and I like it.
That test has always mystified me...I pocket carry. I am too heavy for anyone to pick me up, turn me upside down and shake me. No one has ever done that to me...although I am sure that is a frequent occurrence; other wise there would not be so many people concerned with that test.
My holsters do not need retention straps...If I should fall down and the gun drop out, I would just pick it up and put it back in my pocket holster. Which is a Bianchi, very inexpensive, only about 20 bucks, but an excellent rough-out, stiff leather pocket holster. One of the few real bargains in holsters I have seen.