Scottri:...I can adjust how much insulation I have easier. They don't compress at depth thus lowering the insulating value like neoprene...
These are exactly a couple of the reasons I like crushed neoprene. In anything down to 60 degrees, I just wear shorts and a t-shirt under my suit. Colder and I put on sweats. One layer of sweats does well down to 45 degrees. I can layer if I need to. It's already crushed so there's no compression. And as DA already mentioned, neoprene minimizes air movement through the suit.