Socially it's an excuse to party with everyone you love.
Legally it's only worth it if you have kids, plan to migrate countries, or have shitty immediate family among other things. But if you're just in a long term relationship with your finances otherwise separated, no kids or end of life concerns, ~~then it can be somewhat detrimental as you're just inviting the state in to meddle with your life.~~ it's just a formal interaction with the state.
Edit: see replies.
Yeah i was half awake, a bit harsh ig.
Maybe a better formed argument is that getting into a marriage legally is way too easy compared to the legal process of leaving one. Even if you have all your things in order and everything is completely amicable the dissolution can be a a very drawn out process, especially if you can't be present in the state you were married in.
The part about being in a hospital, only applies if the partner is not conscious, otherwise they can consent. Some other counties have another method for this where if you've simply lived together long enough those sorts of protections exist. So yeah you have a fair argument in the US. Is it a valid reason for legally formalizing your marriage? That's up to you and your partner to decide.
I think my major annoyance is that people put emotional value into the legal matter of marriage as though law and the state had some interpersonal value.