Alright, here are my problems with gen 3/3.5 :
There is no conflict, even if there are "antagonist" they aren't really even evil, nonetheless bad! It's like telling your kids "Nothing bad ever happens, everything is just sugar coated sunshine, and happiness!" Mario Sunshine has Sunshine in the title, and it isn't nearly as innocent!
The lessons aren't even necessary to teach children. There aren't really any good lessons, and all of the things they do "teach" you can just learn from Friendship is Magic. Infact FIM teaches lessons even adults can find helpful!
The dialogue and music is dreadful! It seems the writers just gave up! You know, the best kid shows, are written for the WRITERS enjoyment, not what they THINK what small children like. And the music, isn't even catchy, have you heard Pinkie Pie's singing in gen 3?
And don't even get me started on the designs. "Who needs color pallets? Just give them rainbow hair! Even though that should be RAINBOW DASH exclusive."
Point, made.