Yes, I'm 100% in favor of living together before marriage. I am not sure if my friend did or not - I know they both owned their own homes, so maybe they didn't move in together until they were married and bought a house together? I'll have to ask. Great point though.
My personal opinion is that marriage is outdated and cohabitating isn't necessary to have a fulfilling relationship - and actually adds unnecessary stress. I think most people do it for the financial benefits which is fine... until it's not. lol.