I have done some light bushwacking in tights and I haven’t found them nearly as fragile as you guys are suggesting. I was not using the thin soft tights that you see many women wearing, I use the midweight running tights with material that is far more robust. The fabric on my old, now deceased, golite tights felt like a super light version of the material you see on many stretch woven pants.
They do take a beating and get holes but for trips that involves short sections of off trail bushwacking or primarily off trail trips in more open environments (like closed canopy forests) I don’t worry about it. They pair well with some light nylon pants which provide both brush and wind protection while the tights provide light insulation.
The thing that really destroys clothing and makes you bleed are sharp broken sticks. I try to be careful crossing deadfall. I have never run into thorns walking off trail in my local environment other than blackberry bushes which can be avoided.

