I will put up my "analysis" tonight, but for now I'd like to quick hit on the "forced commitment" aspect of the marriage contract. I find this "burning the ships" effect to be an interesting one of human-nature... that is, that there is some benefit to giving yourself no easy outs for the purposes of increasing commitment to the shared outcome.
I find this to be a questionable analysis (I think it would be similarly easy to argue that the "rigidity" of a marriage contract can have equally damaging effects to how some engage in their relationship (similar to how Harry Browne discussed the topic (interestingly, he did eventually get married, so perhaps that isn't the best examble)).
But even if I accepted that there's certain benefits to putting some "commitment rigidity" around one's shared life with another, I guess I'd have to say I think it would be healthiest to do it in the most intentional and simultaneously beneficial way possible, and if a state marriage is anywhere near the top of that list. For instance, I don't know how many people I meet who are grossly under-insured, lie to their spouse, have little/no financial accountability mechanisms between them and their spouse, don't reconcile their priorities well, and don't have any of the actual GOOD legal documents (PoA, medical directive, living trust (possibly), ToD deed on home, etc) that involve MORE intentionalism than a marriage contract, but the upside/downside is significantly better.
Simply put, state marriage contracts are a random "commitment-ensuring" rigidity that people seem to want to use as an excuse to not do any sort of intentional risk-management planning that offer far better "ROI" in terms of the actual benefits. And really, how much commitment do they really ensure? They don't prevent a spouse from cheating. They don't prevent financial or emotional abuse. They don't ensure respect in a relationship (in-fact they allow abuse (emotional or physical) to have much more delayed and difficult response mechanisms. They don't ensure financial security, and in some ways make it more difficult to accomplish.
It just seems to me until people actually get intentional about the rest of this stuff, they have NO business creating an artificial loyalty mechanism via rigid contracts that become an expensive nightmare to detangle. If your relationship needs the latter and doesn't receive the former, it's a sloppy one. If it has the former, IMO, it doesn't need the latter. You've already set the table for a healthy relationship. It would be like starting a business with a partner you have a decent level of respect for, but getting a complex and incredibly difficult to disengage from partnership contract when you barely understand business fundamentals.
But I haven't really explored the "cost/benefit" analysis yet (not trying to be lazy), nor the "alternatives" that one can engage in planning-wise to ensure a far-more secure scenario than being married (unless, of course, you find yourself in a position where your spouse is being asked to testify against you in a criminal matter).
But seriously, if people have other examples of situations where the legal status of being married comes with some stark financial/legal/lifestyle benefits over simply being committed spouses in every other way minus the contract, I'd love to find more. I've tried to find them online, but I've found that the arguments are very, very weak when I scratch the surface a bit. The "tax" benefit alone, I would guess, applies to at-most 50% of the population, just as an example... and often it is a cost, not a benefit... and large-ones at that.
The biggest one I can think of is the ability to have visitation and family leave rights during a health crisis... God-forbid you actually see the wrong side of that. But I'm half-confident that one could simply have a medical directive and a very solid life/disability insurance safety-net (two things you should have anyway)to get you out of that one. If some of the healthcare or legal professionals here could lend their insight on the visitation/medical-directive piece, that would be great, because that alone could tip the scales for a lot of people who've been through a nasty family health event.