I wouldn't give up Empire (or even Jedi or Revenge, really) but I can understand that view. You can't underestimate the simple "purity" of that first movie, for a lot of people, that's THE reason to be into Star Wars, that is the essence of its charm and a larger "saga" with everything explained and resolved is almost a complete 180 from that. A scifi/fantasy "franchise" is a more ordinary thing, we have lots of those.