When did Star Wars stop being fun? Probably when I realized that Lucas hates me.
It wasn't ROTJ. I know ROTJ wasn't near as good as SW or ESB, but Star Wars was still crazy fun.
Before 1997 every edition of SW that Lucas "made" me buy got better and better and better. VHS! VHS letterboxed! Laser disc!
Even the SEs were an amusing curiosity. And on the big screen!
But then Lucas declared the SEs the "real" movies the way he "always wanted them". Then he starts making new Star Wars content and it's all PT stuff. (I like Clone Wars, but do the same treatment for an OT show and I'll be in heaven.)
The real nail in the coffin was when he put the SEs and the OUT on DVD "so the fans can decide" and he 1) gives us the OUT in 4:3 letterboxed and 2) does a pretty crappy job at transferring the SEs!
BUT - having just watched SW and ESB on my 50" widescreen in anamorphic glory (I'm not sure which version, but I'd take any links to the "best" OUT version) AND watching Star Wars: Revisited with my 8 month old son in my lap and my 2 year old daughter snuggled next to me:
Star Wars is still crazy fun.