Ah, the shock mounts are just about as low as the differential so it kind of makes sense. On mine anyway, and, I'd wondered about that exposure.
I don't think you have to be specifically rock crawling to need protection (leaving aside for what). It can often be the case that you are on a back road / fire road and there are rocks, could even be pointy, sticking up, they can be part of the bedrock so stuck there and if there is no way around it you have to go over it. Or turn around and go home.
It's really a matter of inches. Say you pick a good path and you clear the rock by 1/4". All is fine. Say you don't clear it by 3/4". You will hit/scrape something. If you're off by 2", I'd say you probably will be hung up.
Where you'd hit, say, a fuel tank skid pate, is way above where you'd hit the differential, so you're trying to choose a path that works, of course, but depending on the surface (slippery?), you can move off your intended path.
Granted I'm probably the most inexperienced off-roader here, but it's geometry, you look at the underside of the truck and try to keep in your head what that looks like, then choose what path doesn't hit anything. I think this is where experience comes in, because you're not getting out and measuring outcrops with a ruler.
There are three possible situations: one, there's no visible issue, so no problem, two, there's a massive issue, clearly not passable with the vehicle. Those are easy decisions. The third situation is when it's probably/maybe ok if you take the right path/approach and the truck stays on that line, and those are the hard ones to know what to do especially for an inexperienced person.
I'll gain probably 1-1/2" height just by putting on new correct size tires. It doesn't sound like much, but it's a lot. Would 6" be better, sure, but dealing with what I have, I'd want to maximize height insofar as I can without making other changes at least right now.