And now we get to the actual political meat of the problem. I understand your concern, and share it, since it then would affect me individually, however here is where the at udes split up: some people don't really care about tradition and will like to afford these people the possibility of better integrating to society (provided the therapy works for them, and being cognizant there's a fine line), and other people feel themselves uncomfortable with breaking tradition and the potential slippery slopes (that when you actually dig a bit deeper, have a lot to do with what's 'normal', where 'normal' means traditional social constructs), and they rather just close the door to this threat to their traditional values from the get go.
This doesn't happen just with this specific issue, we've gone through this with a lot of items: from same sex marriage, to religion, to women's suffrage, to slavery, to political correctness, to immigration (ie: DACA). So this really isn't new, just part of a general shift of looking at ourselves and our social rules and re-prioritizing what we individually think it's important.
And that's actually rational. Also rational is for people that are suffering greatly in the framework of our social construct due to it, that they'll seek solutions to that suffering. Whether they're a minority or a majority is really immaterial in so far as that their struggle is real. Rationality and tradition are not the same, and they don't go hand in hand. As I pointed out before, the fact that men could only vote was irrational on it's face. It took a fairly massive social movement to change that however, and now we look at that as the normal, but it clearly wasn't back then, and at some point it was also a fringe. It also opened the same slippery slope you mention, things like what happens when women are a majority and their vote decide who our president is going to be, which would affect everybody. We can also surmise that the notion of a change in the status quo prompted dysphoria on the majority at the time.
So, personally, I'm not that big of a fan of social traditions and I don't fear them going away. I find some of them arbitrary, and sometimes even irrational. I'm also mindful that if you indulge too deep into that, you could end up in the moral relativism end, which is also a trap. So there's a careful balance, and there has to be a constant re-evaluation of where we're at and where we're headed. With the advances in science, this will only get more pronounced. From IVF, to AI, there's much bigger possibilities for disruption (and thus, social unease), and I honestly don't think people can just obviate this or outright forbid it, if they want to shape it.