Well their are good points on both sides for and for not having the strap. I've made and make them both ways. The ones without a strap aint gonna come out it their molded right and the knife is put back back in the sheath where it belongs.
On the straps i see lots of them put on where the snap is facing the wrong way and hang on ever piece of brush and limb that it comes in contact with ans their going get unsnaped. In that case IMO the knife is more likely to get lost.
Thousands of holster's have been made without a strap to hold the pistol in and i doubt many if any have been lost if was formed right and the gun put put back in right. Plus a cheap gun cost more than $300.00 anymore. Not i would want to lose either one. I hate to lose a cheap pocket knife, change or anything else out of my pocket for that matter.
Main thing is people see some big name person doing what ever a certain way or wearing what ever and they want it done or to do the same way, same thing. Wrangler jeans are a good example of that. Next time to run into somebody that has a horse or horses and i bet most of em have Wranglers on. Wrangler spent no telling what to have big name rodeo people to wear their jeans and round here anyway everbody thinks they have to wear Wranglers if they have a horse. It doesn't make it right but that's the way it is.