The producers of Singing in the Rain didn't try, or try hard enough, to make a good movie?
For those who haven't been paying attention, the issue is not
whether people, young or old, like this or that. The issue is why they refuse to even try. And, secondarily, why they get so bent out of shape when someone notes that it isn't very sophisticated, maybe even kind of dumb, to judge something (really, anything) so superficially. Older people who won't watch anything because it's popular with young people are obviously indulging a mean streak, not using better taste. Ditto for young people refusing to engage with anything old.
And no, pretending you're MST3K isn't watching, it's performing.
That said, I must admit that younger actors tend to be less skilled than older ones.
I think it's because they've had less practice.