Well, it really is a place to try to do creative stuff. Its also sort of a meta-game between the deck builders and the farmers, each adapting to the decks in there based on the little information they get rather than actually having a clue what they'll face. The farmer needs to see the random decks they face and adapt based on them and assume that it will continue to follow that trend. The Deck Builder needs to see what decks win and lose and try to discern what decks are being used, and make counter-decks, assuming that 'those' won't change. Its a strange and interesting game.
Also, I'd like to think I've made at least a few decks outside the norm.
As a side-note, from my studies I can give a bit of statistics of plat-league games ratings over the population. Pretty much no deck will ever get less than 30%, and pretty much no deck will get over 60%, assuming that the sample size gets large enough to get rid of flux. Also, creativity isn't determined too much by how effective the deck is, but more by if it annoys the playerbase. For example, a
Mindgate deck that runs mindgate off of Supernovas will get the same thumbs up as a generic SoSa Stall. Strangely, Flying Tridents also gets a ~35% approval rating, while Adrenapests gets over 50%. (Wasn't quite standard adrenapests, admittedly)
From all the data so far annoyance is largely caused by three things.
1. A card that player doesn't like regardless of actual effectiveness. (SoSa, Dimensional Shield, Discord, Steal, Supernova)
2. Its a 'overused/hated/generic element'. (Fire, Aether, Death, Dark)
3. The deck is aggravating to play against, regardless of actual effectiveness. (Earthquake, Nightmare, Fractal-Ball Lightning-Bonewall)
Sidenote: I can't say anything about rainbows since I haven't actually listed any rainbows, speedbow or otherwise, since the system came up.
Generally, 25-35 is a 'bad' approval rating, while 45-60 is a 'good' approval rating. Assuming over 20 votes to eliminate strata its almost impossible to get over 60-70, as is seen by the good portion of people here that auto-thumbs down.