I think when the original work is considered iconic, even if recreating it is not a contractual requirement as it is on some of Jerome Robbins' work, there is fear that audiences will reject anything except a copy of the previous work. It's why shows like A CHORUS LINE will never satisfy again the way they did originally.
I wish directors and choreographers were bolder and producers had less fear. Wouldn't it be thrilling if we got a new A CHORUS LINE every 10 or 20 years with new, original choreography by a director/choreographer with the guts to take it on and do it? Wouldn't it be fun to see what Warren Carlyle could with HELLO, DOLLY! without relying on Gower Champion? Or what Jerry Zaks might do? Or what Santo Loquasto might do with the costumes if he didn't feel the need to make yet another red dress?