There is a long running thread on this very issue
here enjoy reading it and make up your mind.
I think most folks thinks that this sort of stuff is OK to wear if you fly something which was not very ergonomically designed and with 'normal' clothing you may get stuck behind levers etc.
For flying most GA stuff they seem a bit over the top, although the fire retardant properties can not be shunned if it is the proper Nomex stuff.
FD