Sometimes you need nothing more than skin protection; sometimes you need something like armour to protect you from a very hostile environment.
Often what is required is somewhere between those two ends of the spectrum.
In most cases, a good fit is a really big deal. Ideally you don’t fight the cave (it tends to win) but there is even less reason to be fighting your kit – you should have similar mobility in an oversuit as you have in normal clothes.
We have a wide variety of suits because cavers come in a wide variety of shapes…