Oh it's absolutely an age thing. Star Wars has always been geared for a younger audience. George Lucas even has an interview where he says "I'll get in trouble for saying this but Star Wars is for kids". The prequels really tested this. They're not super great movies to begin with but they were a significant tonal shift from the Original trilogy. I shit thee not on this but all the animosity the Sequels get? The exact same level of energy and anger that the Prequels got. That only started phasing out once Force Awakens came out. Suddenly everyone loves the whole prequels. Star Trek has similar arguments (see Discovery or TNG when it launched. Or DS9 when it launched. Or Voyager. Etc.) but they aren't as loud about it as Star Wars can be.

I'll echo Stamet's statements (heh). The vitriol for the sequels, if anything, is softer in a lot of ways than it was for the sequels.

Jake Lloyd was massively bullied (by classmates and fans) to the point he wanted nothing to do with any of it. Ahmed Best has been pretty open about considering suicide. Hayden Christensen got a lot of hate as well. It's hard to find raw things from the era unless you happen to know forum links and such. The article below makes it seem a lot smoother but I think the quoted bit helps a little.

And then again, at the end:

[In his home], he has a series of large metal letters that spell out a motto: ILLEGITIMI NON CARBORUNDUM. “It was a saying among soldiers in World War II,” he explains. “It means ‘Don’t let the bastards get you down.’”

As far as RotJ it's hard to understand how much the die hard fans hated the Ewoks now. Imagine the criticisms you raised above being focused onto a single portion of one movie. The anger I've seen over Canto Bight being unnecessary doesn't even touch it.

It's absolutely an age thing and I'm confident the sequels in twenty years will be largely as received as the prequels are now and you can have this side of the conversation with some young fan upset with the new thing that's ruining all of it.