I would not say it's ruined, per se. Changed, for sure. Expanded, maybe. You could perhaps even argue it was highjacked. But not ruined.
Even original GB tended to include gender identity in some form, even if nobody would call it trans then. Gender-bent characters would express their denial, later confusion and finally acceptance. But compared to explicitly trans stories, it was more subdued, and often used for comedic effect.
As for me, I have not tired of them yet. I'm more cautious when choosing them, as a good number of them now have significant focus on gender identity and subsequently the related politics/political correctness. They can be so foccussed on it, they forget to tell an actual story. Those are always a turn-off. But there are trans stories which get the balance right, neither drowning in the topic, nor glossing over it, and there are still some traditional GB stories too.
In my opinion, gender bender is not the same as trans, and should not be treated as such. Ostensibly, trans is a form of gender bender, but gender bender does not have to be trans, depending on the intended theme and focus.
Trans obviously deals more with the... well, trans topics, while GB focusses less on those aspects, and more on just swapping the gender of a character - either a pre-existing one, or one created for the story - which understandably comes with typically feminine or masculine traits.
