I wish there was a way when making the park reservations to be able to pre-purchase a key to pick up on your first DL reservation day. That way DL could manage the inventory and track 1 key per ticket. That way anyone who wants one can at least get one. If there are extras then that's open to all (although I am also disgusted with resellers but have felt that way for decades as an avid concert-goer. I will not buy anything from a scalper/reseller, period.).
Having said that, DL designed the key with all the unique pins so they are hoping some people will keep buying the keys to be able to get all the pins, so clearly this is on "Frozen" scale, in that they grossly underestimated the demand. For those who recall when Frozen came out (my daughter was 4 so I lived through this), there was almost no Frozen merch anywhere- no dolls, costumes, party decorations, etc. for many months and what was available would sell out immediately -and the movie came out at the start of the the Christmas shopping season. With millions of little girls dreaming of that Frozen birthday party and wanting that Anna or Elsa (in most case both) dress. I'll bet the Disney marketing person for Frozen got fired after that mess. Huge opportunity loss.