I don't know that anyone here is claiming that all Disney movies used to be artistically great. That was never the case, regardless of the era or management team.
For every Mary Poppins, Walt had a The Ugly Dachshund and The Happiest Millionaire.
For every Herbie The Love Bug, Card Walker had a The Computer Wore Tennis Shoes and The Boatniks.
For every Pete's Dragon, Ron Miller had a The Last Flight of Noah's Ark and a Herbie Goes Bananas.
For every The Little Mermaid, Michael Eisner had a The Rescuers Down Under and a Treasure Planet.
But what changed is the automatic assumption of parents that those movies were appropriate for their children. Now many parents are on guard for media products branded "Disney", and that's a huge cultural shift. And the brand suffers for it.