Here's why: there's this one quote in the movie 'What happens in Vegas' that I effin admire... the judge declares that it's not gays that ruin marriage, but people that go to Vegas (or a place similar to it, or no where really) and get married on impulse, and then go on and get divorces... therefore, treating marriage like a bit, fat, joke.
Seriously, marriages should be banned in places like Vegas, places loaded with alcohol and immature behavior, banned for people that have known each other, perhaps, for less than a year, people that treat marriage like a piece of shit. At LEAST gays are fighting for the goddamn thing out of respect, integrity, and love.
So, yes, gays should have the right to marry because they're more serious about it than the common straight couple is. I don't care what's in between someone's fucking legs, it's the motives, desire, commitment and love that counts.