I'd be hesitant to view marriage as a financial partnership though. To me, marriage is more of a life partnership where both parties are "all in". A lot of the benefits of having a "life partner" stem from having someone who unconditionally watches your back and keeps your needs in mind. You can't put a price on that type of a partnership by definition (you introduce a monetary condition).
I agree that someone with real wealth could hire folks to manage their assets, administrate, listen to their thoughts/concerns, provide intimacy, etc, at the cost of a fraction of their net worth well below 50%.
Maybe people worried about protecting their wealth should just hire out those roles instead of getting married. I wonder why they don't. :)