I've had the worst luck both getting anything rare from any of the crates I've opened. I just don't understand how this randomizer works. For instance, if there's a 1/9 of getting Leroy, why I have I opened 40+ crates with nothing good & there's people out here with 3 Leroys? I obviously don't have luck (both in crates and finding decent trades), and I'd hate for more of the super rares from the original being released this way.
Once quests are released, I think that would be the best way to earn keys and/or super rares (like bird hat/inferno, etc.). They could still be "super-rare" if the quest is only open for a day, or three days. If anyone remembers the search for Blackheart's treasure in 2008, you could win a Minnie hat, tons of credit, and treasure detector magic. It was open for less than a week, and it was a huge success because it was attainable for everyone, not just people who happen to be really lucky.
If keys and crates are in the game to stay, I think that keys should still be given randomly through playing mini-games and random events (i.e. "find Amy!"). However, I think different crates should go on sale. There could be standard crates (which are the items being released in Crate #1, not including "super rare"), holiday crates (which guarantee a type of holiday item), pin crates (guarantee regular pins and/or magic pins), and clothing crates (that guarantee anything from hats to shirts and shoes). Depending on the type of crate, the higher the price. The gold key could be used to access any of them, and you could buy the crates of the type of items that cater to your wants. Each crate-type will have their own set of average, rare, and super rares. For instance, in the pin crates, the super rare could be a magic like Fireworks magic, a rare would be Haunted Mansion pin, and an average could be one that was already released in the past or a catalog pin.
Again, this is only a suggestion. It would be something that would still make other people happy. (Especially since people have tried so hard to collect keys, it would be a shame to see them be out for sale.)