Well, the simple fact is that Prince understands how to make the material interesting on stage as opposed to interesting on record. One of the major problems with musicals that begin as "concept albums" is that the tend to be expository, which was the chief issue with the last revival (this is also why I believe Jesus Christ Superstar has never had a successful production - albeit for the opposite reason: Evita needs a concept, Superstar is hindered by one). Prince knew this and, with minimal rewrites, created an extraordinary and theatrically thrilling event that made Evita into a concept musical as opposed to a narrative musical. Even the Times, who didn't like the show that much, recognized the strength of Prince's direction while condemning the vague strokes Rice drew the primary characters in.
The revival tried to soften the role of Evita, make her more "likeable". This doesn't work with the character as written, and all it did was stop her from belting the more thrilling notes of the score, instead moving to falsetto. The addition of "You Must Love Me" is unnecessary and gives Eva three big ballads in act two, for no reason. Besides, it's a song added for a diva in the film version, hoping to get an Oscar, and it shows. It doesn't blend with the rest of the score (along with Superstar, Webber's most cohesive) and what does it really add to the story? Another generic pop song? I wouldn't have been surprised had I learned Glenn Slater had served as lyricist as opposed to Rice.
"Sticks and stones, sister. Here, have a Valium." - Patti LuPone, a Memoir