You can do paperwork for these things

Please explain to me how exactly could I "do paperwork" to restore, for example the spousal communications privilege and the spousal testimonial privilege that would both be taken away from me if my marriage was dissolved.

And do you really expect people to just start pre-emptively filling out paperwork to notify every single hospital they might possibly ever end up in after some major health issue, that would allow their spouse to visit them, particularly if it's a hospital in an area hostile to queer folks?

Paperwork didn't help the partners of AIDS victims who were kept out of the hospital and heard of their partner's passing via the obituaries and then kicked out of their house.

Even today, there are families who would separate sane sex partners and do the same awful things. Marriage guarantees rights, paperwork does nothing to stop the horrible people in our lives that would lash out at the first chance.

The laws for POA would have to change to allow for such a union. There would have to be some kind of protection for wills as well, because there are going to be fights from people against the LGBTQ community.

If all marriages were dissolved and became unions, that might work. Otherwise, it would be a separate but equal thing.