It is understandable that those people who are against gay equality are against marriage equality. However, that is stupid.
Marriage equality has been said to 'fracture' gay communities. I believe some degree of this will happen. The gay identity will never be the same again, meanwhile, marriage will always be almost overwhelmingly (97%+) straight. Since majority rules, and 2% of people don't usually get a say in defining any culture, marriage will be culturally constructed in a straight way as it always has been. Gay couples living under marriage will be a like a racial minority living in a country that doesn't even want to speak of multiculturalism. There will never be any special accommodation for gay couples even when they actually need it, because identical treatment is all a minority can usually demand - and sometimes they even get inferior treatment (e.g. some places where gay marriage is legal gay IVF is banned). Meanwhile, those gay couples not living under marriage will be seen as unstable. This is because they will have no other legally and socially recognised bond to resort to. They will likely become a voiceless underclass.
I personally support marriage equality for various reasons, but I do not think it will bring 'gay equality'. Marriage equality will come at a price, but it is a price to the gay community, and I think they accept it, so I am happy to support marriage equality. For the straight community, marriage has always, and will always, be theirs either way, because of demographics. They have nothing to fear.