User blog comment:JAlbor/League of Legends Community Awards 2013/@comment-11603965-20131220232203/@comment-5331854-20131223103138

About TPA and Riot Skins: They're still exclusive because you can't get them directly. The only way to get them directly was in the past when they were promotional skins. You may begin bitching when they're giving out "achievement skins", like the Victorious series, King Rammus or UFO Corki (I'd like to have King Rammus, but I know and understand why it's exclusive and it's on a whole higher level than the "Limited Skins" like Kitty Kat Katarina where the only "achievement" is having played earlier than other players).

In short: Buyable achievement skins will start the First Grand-scale Cyber War, the Third World War, open the portals to the nine circles of hell, flares a light that attracts Tyranids and Zergs and makes the ancestor of the God-Emperor (who is living right now) commit suicide. So Rito won't do that.