I once again bring forth my favourite heresy:
The biggest problem with the Star Wars franchise is ...
... The Empire Strikes Back.
Why?
Because it raised the bar too high.
In Star Wars (now A New Hope, but I stick the original name) we had a whopping great Saturday afternoon matinee bubblegum flick. It was WHIZ, BANG, WOW, with a minimal script, cheesy acting, and propped up primarily by special effects. Was it good matinee fair? Yep. Was it Fantastic Cinema? Nope, not really.
Then came Empire. Here we had serious character development, deep menace, and the all important, "Luke, I am your father!" The script was tighter, the action more impressive, and the stakes incredibly high. This film also had the least direct input by George Lucas. That may have something to say about it.
Since then the films went back to Saturday mantinee fair. Not too bad, but certainly nothing deep, great, or important. They are special effects driven films with too many Kewt Things (ewoks, JarJar, Li'l Luke, etc.), but the depth and the mythological resonance of ESB is gone.
So, if ESB hadn't raised the bar, Star Wars, as a series, would just be a cult series, probably not this long, and certainly with no huge level of anticipation, or such crushing levels of disappointment.
So the problem with the whole series, my opinion only, of course, was the one truly brilliant film in the series.