Does it make more sense to change Visa laws to allow more flexible relationships? Would you then not need to be 'married' and just use your partnership status?
Changing all the specific legal benefits, privileges, and obligations of marriage to be "marriage or partnership" makes less sense than changing the admission criteria for marriage.
I mean, this is a tech forum, right, think about it from DRY perspective.
Gay marriage is now legal in the UK. Are you suggesting that it would make "more sense" now to abolish gay marriage and try to adjust 100s of other laws and regulations to prevent any disadvantage to gay people? Surely this must be a disingenuous suggestion.