Maybe it's because I was 9 when it came out
This. Jar Jar is pretty awesome when you're a kid.
Ewoks are also awesome when you're a kid. But when I look back at RotJ, I realize that the little bastards just didn't belong and detracted from the main storyline.
I do remember laughing at the Ewok whacking himself with the sling. I do remember laughing at how clever it was that Chewbacca did the Tarzan yell. I even laughed at both burp jokes.
Today, I shake my head at those scenes and wish it kept the same tone as IV and V.
So, yeah, I'm not arguing that Jar Jar isn't awesome for kids, but his inclusion not only didn't contribute anything worthwhile to the movie, but it actually detracted from the main storyline (as flimsy as it was).
But there's a lot to be said about nostalgia. I have fond memories growing up with Commando and will probably watch it again if it comes on. But it's a bad movie, no doubt about it. There is a difference in how two people can view the same movie if one is a kid while the other is an adult.