"For the past year, we've been exploring ways to solve a conundrum with Limited Edition skins. Here's the crux of the issue:
-During events from December 2009 through October 2011, we released 34 skins for a limited time and communicated they wouldn't come back into the store.
-Since then, our playerbase has grown so much that these skins are virtually never seen in game
-Every day we receive heartfelt emails with compelling stories from players asking for the chance to own or gift their favorite skin, either because they missed the brief store window due to travel, illness, deployment, etc., or because they hadn't joined the LoL community yet."
These are Riot's own words from the page about the event, They told people it would not be made available again so basically they lied. They can go on about these "heartfelt" e-mails and skins like bewitching Nidalee only being seen every thousand games (I've only played for about a year and personally I have seen this skin used more than just about every Lux skin) but they are doing for one thing GREED they want the all the monies. I don't own any of these skins in fact I don't own ANY skins and while I have always wanted Christmas Sona and kittykat I'm still more upset than happy.
If people bought something under the assumption that it would not be for sale again and then it is of course they get angry or feel "entitled" as you put it but to me entitlement looks more like "Why do these guys who played for years and years get something I don't? I WANT IT RIGHT NOW!"