Good job Hasbro. No seriously. Good. Freakin' Job.
This reminds me so much of the whole South Park thing back in 2010. Why do a bunch of whiny morons have to ruin such a good thing? There's always gotta be that ONE person who has to kill everyone's fun.
Y'know, is this really what we as a race are coming to? Being offended by cartoon ponies? What's next? Are we going to become offended by...I don't know milk or something? Are we no longer going to be able to call our pets cats or dogs but "Vertically Challenged Quadrupeds"? Are we going to be able to sue other people for giving their own opinions on something?
OK, those examples are a bit extreme but you get my point. Political correctness is completely ridiculous. When you open your mouth, you run the risk of offending someone. It doesn't matter what you say. With all the horrible things that are out there, all the horrible things you can say to someone, is a cute, innocent cartoon pony really that bad?
I could understand if the characters made fun of Derpy or if Dash called her an idiot or a retard but they didn't. And Derpy's none of those things. I don't necessarily think Derpy's an idiot or anything like that. More of a klutz. That doesn't exactly make her dumb or offensive to those with disabilities. As for her eyes? What's so bad about her being cross eyed? Originally it was an animation error but the creators rolled with it when they saw how much love Derpy was getting. Derpy's crossed eyes are what make her Derpy. They're what make her stand out from all the other background ponies. Without them, she's just another generic background pony.
tl;dr, Political Correctness can go die in a hole and Hasbro are a bunch of cowards.