Watch insulating hosing though. It promotes heat in the engine bay. It is very handy for some vaccum lining, but some lines you do not want to maintain heat.

I think what you are talking about is the insulation around your power brake line. That shouldnt be a biggy. The insulation on it is simply a protection from the heat that the engine creates anyways. It's simply precautionary. It wouldnt hurt NOT to have it, but for visual purposes, any auto supply outlet should have some.