I forgive them for the nylon hair on all their toys. The entire gimmick of the My Little Pony line has always been the brushable mane and tail, so it's something they need to include. If they didn't then the classic collectors would complain and they've been buying these thing a lot longer than the bronies have.
And the Pink Princess Celestia thing has already been addressed: The toy guys wanted a pink toy because pink toys sell better to little girls. Celestia toys were pink until Cadance was introduced, so now bronies get show accurate Celestias and little girls get their pink ponies.
As for why the bodies are always off-model... It's because it's expensive as hell to make molds for these things, so you always want to make one you can re-use for another toy. Transformers have the same problem and it's fandom makes the same complaints. Unfortunately, until the community is willing to pay hundreds of dollars for a toy like the Transformers fans are, you ain't going to see special figures outside of some sets.