I guess I don't understand a musical.
With most film genres, even ones I don't like, I can kind of at least attempt top appreciate what is happening based all of the things that make most types of films, regardless of the genre, work. Things like, tension, suspense, humor, what's important to character, how a screenplay is constructed, and how various aspects lead to various payoffs. But, in musicals, there is so much gimmickry, so much distraction, and in the case of this film, the characters are singing about everything, and these songs can't possibly exist in the same time frame and dramatic word as the rest of events, because once a song starts, I become disconnected from the material.
Compare to my favorite musical: Oliver!
The songs are memorable, and the story is fantastic, and the songs tend to accentuate the narrative and build character. They never bring the narrative to halt. Same with most Disney films. But Moulin Rouge
has no tension, no reason to be hooked, and the songs - as well as the visuals that accompany them - are distracting. And just because the songs are differently arranged than when we've heard them before still doesn't make them sound new or original.