I have never thought of Cinderella as either mental or someone with a foot fetish. But apparently it occurred to Douglas Carter Beane, who has written the book for the new version of R&H's Cinderella.
Here's a comment from an interview with Playbill:
For Cinderella, the research stretched back to the 17th century, to the original 1697 story by Frenchman Charles Perrault. "As I read it, I thought, that's really good," recalled Beane. "It was a really smart story. It wasn't a story where Cinderella was this psychotic waif who was prince-stalking and had foot fetishes. It was social satire. I thought, that's my way in."