XC or recreational trail riding, probably not, but if you're into enduro, freeride or downhill, you can (should) already be wearing a lot of really bulky gear. Heavy duty boots with toe protection, pads for your knees, hips, elbows, gloves, spine and chest protectors, neck braces, full face helmets with MIPS

I believe some kind of airbag solution could actually be really helpful, but here's the thing about falls in MTB: they happen quite often and they're usually harmless, sometimes you even toss the bike on purpose when you realize you've messed up or miscalculated a feature.

And you probably don't want to replace an expensive gas [generator] cartridge or suffer burns or just have to endure loud pops every time you make a mistake.