I agree to a point (see my #3)
in my world...Govt. would not be involved with marriage....all those legal things that are determined by a legal partnership...should be just that...a legal partnership
let the churches determine marriage protocol and hand out their churches marriage certificates and let the govt hand out a partnership certificate at the same time or by itself if no church marriage is performed..
To whom? Any two people who apply? Any two people living together? Any two people who can prove they're in some kind of genital contact? Why two people and not three, four, or twelve?
There is a legitimate economic interest for people who want to establish the range of economic provisions that are generally aggregated under "marriage." A parent with a dependent adult child ... a person with a dependent parent or other elderly family ... siblings sharing a residence ... friends who want to face the world as an economic unit. I think there should be a provision such as "contractual household," which puts those legal arrangements in one basket, as it were.