Because we can do something about the cards; we can't do anything about the tickets right now: that belongs to thor and storm.
The thing about a deck rating idea being implemented right now (without reset) is that all the wrongs commited when decks were "unrated" would still exist; people would still have all the wins/losses that they got (notice how I didn't use the word 'earn',) when things were imperfect. If we added a rating system and reset it, people would thus earn all of their wins and losses fairly from now on (hopefully.)