If mass appeal doesn't matter, then you are ignoring the fact that most people are average sane, intelligent people. Even if they're Dems. "Quality" is in the eye of the beholder, and generally what the mass says isn't far off the mark. Especially over periods of time.
If Kane is really popular, I'd see alot more of it on TV and in various every-day references, as well as SALES, both of the movies and probably like things on eBay. I never have noticed that. Almost never in a nostalgia or movie-fan store have I ever noticed lots of Kane merchandise. That's an indicator.
What would Kane merchandise be? A sled? Anyway TV, these days, hardly ever shows older movies with the exception of a small handful. It's on TCM all the time. The reason it wasn't a big success in its own day is because it was hindered by William Randolph Hearst's media machine. He wanted to buy every copy and destroy it.