Worst story ever written!
So you have Cinderella who is classically beautiful, kind, sweet, intelligent, hard-working and prudent when it comes to money, and she is stacked up against her two ugly step-sisters who are physically and spiritually ugly, mean, petty, idiotic, vain and frivolous.
The odds are so stacked in Cinderella's favour as far as the Prince falling in love with her because there is absolutely no real competition for his affections. In other words, a completely boring story with no sense of tension or nuance or dimension whatsoever. Characters are either pretty and good or ugly and bad.
What a great message to send to kids, huh? You know, it's what is inside that counts and don't judge a book by its cover...and then we read them or let them watch this crap that associates physical beauty with spiritual beauty.
But that's besides the point. From a storytelling POV it's simply not interesting to make the villains so pathetic and completely outmatched by the heroine. Instead of hating them you end up almost pitying them and their weaknesses.