1. a wedding itself doesn't need to be that expensive
this idea that a wedding should make a woman feel a princess is not just outdated but also stupid. it's an occasion worth celebrating BUT the point is having a marriage, not just a wedding. you'll need the money for a house; projects; kids; etc. to me, that's way more important than spending tens of thousands of dollars on a dress.

2. you are in it together
and again, that's the whole point. from that moment on, you are basically agreeing on sharing the burdens of life together; if you start by not sharing the burden of a wedding, it doesn't speak well for the future.
BUT if one is having dream-wedding expectations and really need them satisfied, that should be on them. if, say, the woman wants to rent a castle and the man really couldn't care, why should he throw in so much money for it? same thing if the guy wants, I don't know, use a fancy sporty car or rent the Rolling Stones as a band.