I get all that. But being able to turn off an infinity stone is a bridge too far for me.....You're... not supposed to like it. That's the point.
Like, I'm fairly certain the whole point of this exercise is to root for Loki to burn down this significant source of predestination, like Loki's whole arc is going to be recognizing that what the TVA is doing is exactly what they professed to want to do on Earth (all that "tyranny of freedom" prattle) and that getting a taste of it themself is will make them realize the flaws in their old tyrannical plans.
I mean... I'm sure there will be the typical MCU twists and turns along the way, and Loki, being Loki, will make non-standard heroic decisions along the way in the name of self-preservation, the TVA will be revealed to be less in control of everything as they appear and/or think they are, yadda yadda, free will and choice will always prevail against predestination, hurray, one last twist at the very end that prepares us for the future, Loki Will Return.
This stuff basically writes itself.
I'm not a fan of any story that is pre-ordained. It was my issue with Eddings' work. It's my issue with any story where the actors have no freedom of will. I can totally get what they are doing, it can be well done, and I can still not like the story. It's why we have so many stories, and kinds of wine or beer.....