I'm sure a lot of people do feel that way. I'm also sure a lot of others don't. By understanding the former but not the latter, you're overselling one sides' feelings. I know fans who feel that TLJ improved on the character of Luke Skywalker by giving him pathos. And I stress that all of these friends are staunch OT fans. That's my particular age group so those are most of the fans I know. That's their bar, not the prequels nor any of the animated works. So not every long-time fan absolutely needed him to be the super buffed all-successful all-powerful Jedi he was portrayed as in the original EU novels. Not everyone needed him to have the ultimate happy ending. There's nothing wrong with NOT agreeing with either of those things. But fans of this nature absolutely exist. If anything you're underestimating that, not the other way around.
I can acknowledge all of this as being someone of the mind that I still wish Rey was his daughter, and that I too am not completely comfortable with the idea of Kylo Ren being the last Skywalker by the time we leave this era. That would be somewhat disappointing to me. But I'm not going to pretend its the only opinion out there.