The show really cannot support another moment without Rose being center stage. It's almost that simple to me. In act one Rose gets a break during "If Mama Were Married..." and "All I Need..." and another number, no matter who sings it, would seriously interfere with the focus of the show and its through-line.
"I'm a comedian, but in my spare time, things bother me." Garry Shandling
Patti also sings "Who Needs Him?"--the solo Styne and Sondheim wrote for Rose in the second act, after Herbie walks out, which was replaced by the reprise of "Small World."
"Who Needs Him?" is a great song, but once again, what's the point? I love "Smile, Girls." It's hysterical, but it's not needed. It's just one of those few shows, where I really feel like everything's already in place. It's sort of like when you watch a special 3 hour director's cut of a previously 2 hour long movie. Sure, some of the new scenes are well written, acted, and shot, but most of the time, I usually go back to the theatrical cut if I feel the need to watch the movie, but I might pull the director's cut out every now and then to watch certain scenes.
Gypsy really had an abundance of great material, didn't it? I usually feel like most songs are cut because they suck, but in this case, every song that was cut was actually quite good.
The sheet music manuscript for Who Needs Him is actually written as Whi Needs Her, and has a much more ambivalent and less dramatic ending. I have heard it posited repeatedly that it is another cut Herbie song rewritten to be a cut Rose song.