Yes.
It conveys tons of automatic rights that you have as a legal couple. Inheritance, power of attorney, sole survivor as well as gov benefits in some catastrophic circumstances.
And that's where you need them most. When something bad happens.
Without the documents, you are just a friend. Nothing more.
You can also accomplish the same thing by hiring an attorney and getting all the documents you need draw up to cover everything but that will cost you 50X what just going getting married will do.
Its kind of like life insurance, as long as everything is going good, you don't need it. But when things go bad, they can get much worse without it.
Y