It has proven to be a much more popular opinion, at least on Hacker News, than I ever would have thought possible in 2014.
FWIW, I supported the unsuccessful civil-union law in my state. I think anyone who wants to form a household and get the economic & regulatory benefits hitherto attached to marriage (insurance, hospital visits &c.) should be permitted to, regardless of sexual activity or indeed its absence (why shouldn't a fraternity, or a few friends, be able to form a civil union in order to get those same benefits?). I don't believe I hold any animus against homosexual folks.
But marriage is just not about sexual attraction, and the idea that it is, is rapidly destroying marriage.