@nh shower-thought: maybe it's a bit like marriage? In the sense that I'm against marriage. I don't like the concept, I don't see the point in involving authorities (state/church) in relationships, and I especially dislike that it can reduce taxes.
However, it exists and is unlikely to go away anytime soon, so it should be available to everyone and I don't blame anyone for marrying for its benefits, esp. regarding immigration, reduced bureaucracy when having children etc