I like rainbows, they are fun and fast.
I think that there are more annoying decks like SoSa abuse, ghostmares, dim locks etc.
I think your desire to encourage of using creative decks should be an encourage to using creative and competitive decks.
Creativity if the deck cannot compete in the actual metagame is not good.
Anyways, Arena will boost new deck ideas, time and metagame will show wich ones are good and preserve in time.