I can certainly understand, it's not easy having adaptions of your favorite show or movie having aspects that aren't faithful (or as viewed by the fan) to the original.
We all have our fandom or movie or whatever and it could feel like a personal insult when what we loved (whether it's actually good is another story) isn't shown the respect its original incarnation was.
That being said, Gen 4 ran for 10 years and its creators seem they gave it a proper send-off.
It might have been easier if they had just introduced these new ponies as friends or something to the original ones, that way gentle autists like Chris might not have been so violently shaken out of their comfort zone....
But who's to say that abruptly introducing Gen 5 didn't give the people at Hasbro a good laugh in the face of crestfallen Bronies?
Eh, I'm on the fence.