Well that's easily said. Whenever someone has locked you and your family inside your house, doused it in oil and put a torch to it, you might have a few regrets. I know I certainly would.
Yes, but nevertheless one must try. Activists too were (and are) threatened with violence, many of them were (and have been) murdered, but if they had let that stop them we wouldn't have made the progress that we have. And we have made progress... surely you can see that? To the point that a popular game can feature gay characters and the world has barely taken notice.
The context of the civil rights movement in the US is very different to the context of elven oppression in DA. The civil rights movement occurred in a modern, democratic, globalised nation that itself existed in a world in which many western countries had already granted equal rights to minorities after centuries of colonialism, two world wars and the rise of the Soviet Union. Thedas meanwhile consists of feudal nations that lack any need to reform their treatment of elves: any uprising is simply crushed and any peaceful calls for more rights are ignored - there is no reason for the upper classes to change the system, and any attempted changes are greeted with hostility. Celene and Maric were both very pro-elven rulers and yet they backslid on any attempt to improve elven lives in order to retain power and control; Loghain personally led an elven company in Ferelden's civil war and yet was ready to sell the Denerim elves into slavery as he perceived that this would give him an advantage against the darkspawn.
One of the few characters in the game interested in actively improving elven lives is Briala, but she only achieves what she does through control of the eluvian network, exploitation of Orlais's Civil War and an alliance with the Inquisition (otherwise she would have no hope). Also, she personally reveres the creators and strives to retain elven culture as much as possible - she isn't simply one to 'integrate' into human culture, and neither are the majority of city elves who seek to protect the elven aspects of their identity.
You make it sound inevitable. It was actually a very tough fight, fraught with casualties. Attempted change was greeted with hostility, not stopping at murder.
It goes without saying that any fight to give equal rights to the elves would have to include all downtrodden sectors of society. They may suppress the elves, but can they purge the alienages and the poor and the peasants and the casteless? No sane leader would be willing to tear their own nation apart (Loghain excepted, but he's dead/gone). If elves were to let go of their isolationist identity and instead find common cause with others, the upper classes and nobility would soon have no choice but to concede to change.
Briala I'm iffy on. Her aims seem good, but she's too focused on her own personal power and utterly lacking in ethics. I get the feeling that she's using the elves rather than working for them, which may be what happens when you hang out with Orlesian royalty for too long.