One issue you don't touch on here is that everyone uses transmedicalist arguments to explain to people why trans rights are important.

If someone declared themselves a polyabodalist, meaning that they had a different conception of where people should sleep than most people do--not always in their own house, a few conservatives might scream about "NO! Everyone must sleep in their OWN house, NO exceptions!" Everyone else would probably go, "Okay, whatever, I think I like having my own place, but you do what works for you! No worries!"

But if then the polyabodalist said they could come sleep in your house any time they wanted just because they felt like it, you'd probably say, "No way, it's my place!" If you decided instead to be polite and said, "Um, I'm not sure about that?" and they called you names and said you were a horrible person, you still probably wouldn't think very much of their request. On the other hand, if it there was a freezing blizzard outside, and they said, "Please--I really need a place to stay, I can't make it out here," you'd likely have a different attitude.

The transmedicalist perspective makes it very clear that the status quo is out in the cold, and there really aren't any other good options. It's a very reasonable ask of society: there is a pressing medical need, and there is a clear medical hypothesis for what is going on and how to help improve matters.

Every other position is much harder to argue for when it is actually an ask for society to change rather than simply for society to let people do what they want. Maybe after talking to the polyabodalist you'd find out that actually they don't want to sleep in your house, they just want you to stop sending the police after them when they park on the street in a convertible instead of a "proper" car. But compared to the transmedicalist reasons, this is a difficult conversation.

So there is something to be said for relieving suffering: it gives a moral clarity and moral urgency that is otherwise absent. It's disingenuous for non-transmedicalists to reject that perspective while simultaneously using transmedicalist reasoning as their go-to argument when interacting with the rest of (non-trans) society.

Maybe there's a persuasive argument along the lines of the one you've made here. There is a good case to allow people to take the path that is best for them (however, the details of how that works out with other people's best-paths are important, and you didn't really touch on that part). But to be fair, it also has to be made not just within the trans community (or even the LBGTQ+-sympathetic community) but with everyone, because society is a negotiation.