I definitely don't think it's too hard, considering the number of people who want to be in the t500, a minumum of deck building knowledge should be required for those who want to stay in.
Also, regarding the fact that the higher the league, the more false god-like advantages a deck gets, it's normal a deck should have a rather large winning rate to be able to compete, especially in Platinum.
I also don't think it's too hard to play them, up to Gold most games can be won quite easily, and it's normal that the winning rate versus Platinum decks goes down, they are FG decks after all...