What's wrong with bagging the rich guy?
Since when a poor girl should be condemned for dreaming of bagging the rich guy?
Who's also nice and hot?
Not to mention that in this story, she is happy to go to the ball for participating at the party, where she happens to meet the hot rich guy, and he happens to like her too.
What's wrong with this scenario? She didn't plan to go to the ball to "seduce" this guy.
It seems to me it's quite a nice fairy tale for little girls: this is ONE scenario, it's never said it's the ONLY possibility for poor girls. So why all the hate against Cinderella and her tale?