I dunno, things like The Godfather and Citizen Kane shouldn't lead to "I love this moment" over and over. They are timeless masterpieces because they can be looked at from so many angles and hold up. These are films that hold up under intense scrutiny, and become better for it. I mean damn, Ebert's done something like 80 shot-by-shot viewings of Kane? These films are fun to nitpick, because like good literature, everything connects and complements everything else.
It has always seemed to me that things like Star Wars and Indy get much discussion because they are not masterpieces, they are icons. Because of this, you get the "I love this moment" from everyone who loves the films and have happy memories with them. What keeps the conversation going and going is the fact that you have fans at various stages of love for the movie.
Some have grown up, matured, moved on, whatever and feel the need to elevate themselves above the ones who still blindly like it. The fight with the ones that need to validate the movie they love, even though they've started noticing the warts. I've always thought (and I could be totally fucking wrong) that most posts about these sort of movies can be categorized as either condescending or stubborn.
EDIT: I think Dickson is right that masterpieces don't lend themselves to nitpicking. The Indy's and such though, do. They are ripe with the tiny warts and flaws that can be debated over like I mentioned above. The masterpieces should lend themselves to equally lengthy discussion, critique, and appreciation.