Change happens because it needs to.
That's not to discredit the many people who effectuate it, like the civil rights activists of the '50s and '60s or the scores of French revolutionaries. They are a necessary part of change, but not in the way you might expect.
People don't drive the machine; they're the cogs inside. Once society gets to a certain point, things click into place and move forward. Individuals can try to delay it (like the "Yes on 8" people in California), but they never win in the end. Change is a force, and you can try to keep it at bay just like you can keep a plane in the air to fight gravity. Eventually the plane will return to earth, the regressive movement will fall, and the force will win.
That makes it all the more frustrating to find yourself in a situation like the gay rights movement does now. We're going to win - we can feel ourselves hurtling toward equal rights - but someone or other keeps trying to hold us back. Eventually we'll wear this straw man down, and then change will seem to leap forward. But it won't - it'll just finally have taken its course.
Unfortunately for all of us, that includes some changes we might not like (just ask the "Yes on 8" people). If my parents are any indication, by the time I hit 60 I won't be able to use a single piece of modern technology, and if marketing has its way, advertisements will be beamed directly onto our retinas. And of course, that's only if it turns out this same force isn't what's driving climate change. (Just think - how often do you find yourself actively hoping it's all our fault?)
Assuming it's not, I'll be happy to be on the winning side of my pet sociological movement. After all, the winners write the history books, and nothing looks as bad in retrospect as a regressive. What a pity for them that we have all the style!