If you like playing a sport you enjoyed as a child, as a teenager, and as a young adult, are you clinging to nostalgia?
"Clinging to nostalgia?" Not necessarily. But does nostalgia play a key role? Absolutely. The stuff we are exposed to as kids has a critical influence on what we are into as adults. If you are an American, who grew up playing football and baseball, and move to a country where the primary sport is soccer, you're still going to prefer football and baseball. This will continue to be the case even if you are enmeshed into that country for years and become pretty well integrated into that society. The same phenomenon drives most of our collecting habits on this forum.
Same with music, or even politics and religion. There are exceptions of course, but you shouldn't underestimate the impact of formative events and experiences. Can you not relate to Citizen Kane?
Did people love ROTJ in 1983 because of "nostalgia?" That's why we were into Vader and the space battle and Han and Luke and Leia? No, it's just what we were into *period.* It had nothing to do with clinging to the past (all six years of it.) And for millions of people that interest never faded and Disney simply recognized that Lucas went *way* off the rails and is simply righting the ship. Rogue One would have been great in 1986, 1996, and yes 2016.
We were into the original Star Wars movies because they were distinctive and great at appealing to kids at that time. There was nothing else coming close to providing that type of entertainment in that way to kids. Almost all attempts to replicate their success were failures. But yes, a big part of the love of Jedi was the fact that we knew and cared about those characters. Because as much as I defend that film, I also acknowledge that it pales compared to the first and second films. So, without them, if you just plopped Jedi into our laps, I do think it would have been a success. But maybe on the order of Goonies or Gremlins. Something we look fondly back on, but certainly not the cultural touchstone that this franchise was, leading to massively successful sequels and prequels and spinoffs, etc.
I should add though, that I'm not criticizing anyone who supports these movies here. I'm also not trying to use nostalgia as a bad word, though your post characterizes it that way a bit. Just look at my avatar! But I do think there is a limit on what you can do creatively and artistically when the producers, writers, and directors are compelled to harken so strongly back to what worked on us old folks on an emotional level when we were kids in order to have a film succeed today. I don't think they should ignore that aspect completely, but I do think there could be more of a balance, where less of a focus is on reminding us about things that we are nostalgic about. TFA has the basic structure of Episode 4, and the main characters are offspring of the main characters we first saw 40 years ago. Rogue One has countless call-backs to the same film, some justified more than others. We're getting a Han Solo prequel. We'll probably get a Boba Fett and Obi Wan prequel in time. Darth Vader is never going away completely. We'll probably have a half dozen more Death Stars or the equivalent when all is said and done. These things don't occur accidentally.