Scott nailed it.
Illuminating comparison between budget riding jeans and premium jeans ($$$$) here:
https://www.morebikes.co.uk/16621/th...truction-test/
Things to think about
:
1) The abrasion protection in riding jeans comes from a layer of Kevlar. The denim offers zero protection and will be shredded the moment you hit the ground. Therefore riding jeans are sacrificial. One off and they're done, unlike leathers. My street leather pants (AGVSport Willow perforated) cost about $200. Same as a good pair of riding jeans, or even less if you're looking at premium stuff. And if I ever do go down, they'll still be serviceable.
2) The Kevlar is held in place by being sewn to the denim. If the denim gets shredded -- and it will -- what's holding the Kevlar? I'm skeptical on this aspect. I note here that if you go down the abrasion damage will be limited in area (likely your hip, butt, knee) and therefore may well leave the seams intact. Construction is a "get what you pay for" thing.... how much is it worth to you?
3) Leathers don't allow armor and such to move around. Jeans must be loose by comparison to be comfortable. (Hence Scott's wise move of wearing Bohn armor under his riding pants.)
4) If you have to armor up to protect yourself anyway, what's the point of jeans? Might as well wear real riding pants. The only benefit I can see is that you have a pair of "street" pants to walk around in when you get off the bike. Just my $0.02. I'm sure people walk around in these things all the time and don't find the armor awkward.
As Scott noted, it's all a giant compromise. My own choice is to wear leathers because going to the hospital SUCKS and is EXPENSIVE. If I really need street clothes at the other end I just chuck 'em in a pack. Or, for the commute, I keep a pair of pants at work and change them out periodically for washing. If I'm going out to dinner or something like that I take the car.