Aye, it depends on your environment. Gaiters are another factor, if you're wearing them and a long fouly then you're only exposed for a fairly short part of your body. I guess it comes down to having the options.It really depends on the weather I think.
I generally wear cargo type trousers if it's dry, thinner Craghopper style if warm and those + waterproofs if wet. If cold and wet then ski trousers. If very cold, thermals + ski trousers.