When I bought a house (and later sold it), the day before, we had the title company forward all of the documents to our lawyer to review. When he gave his okay, I felt perfectly comfortable signing multiple documents that I never read.
For something like that, it's important to have someone with some knowledge go over things first. Was I really going to be in a position to slowly read over documents for 3 hours and potentially hold up closing just because I didn't understand a contract? No. So, it's best to let a lawyer do his/her job.