Hey, grumpy Disney curmudgeon here. Mary Poppins is a masterpiece. Mary Poppins Returns is very good. It follows the beats of the original too closely (its kind of a musical Force Awakens), but it captures the spirit of the classic, the performances are charming, and while the catchy songs certainly don't come close to surpassing the Sherman Brothers tunes, the production of the musical numbers comes very close to surpassing their older counterparts. It's a real shame it didn't perform even better then it did.
A MP ride would be wonderful but an MPR ride is only very slightly less appealing (why not both?) The problem is the nature of the ride, not the nature of the IP.