I think Lucas is a creative genius who, with the original trilogy, created something truly iconic that will be beloved for generations to come. But the ironies that you point out here, of him creating something out of his control, something that has often inhibited creativity elsewhere amid countless corporate attempts to ape his success, are a tragic part of that legacy.

Leaving aside all nostalgia, I do believe the prequels lack much of what made the original trilogy work so well. I think they could have been far better from a narrative perspective I've even written about what I'd have done if it had been down to me (see below link if you're interested, but please feel free to ignore, as I've already link bombed you once elsewhere in these comments).

The Phantom Menace: Reviewed as if It Were the First Star Wars Film Released | Fanfare