Cancelled Champions(Specifically Omen)

This is my first post so bare with me please.

So we see all these champions being released ever 1-2 months, and I realize riot is trying to make each champion unique from other champions, between the model and the balancing of skills. But why not revisit cancelled champions? There's a list of them, sure, many of them were reworked into other champions, but some are still unique. Such as "Tabu", The voodoo shaman or another member of the Black Rose organization. Surely there are many champions we could revisit.

So my question is: Why not revisit "Omen". I was reading on the wiki page, that Omen was supposed to be released before Riven, but that they had to cancel him for some reason and had to push up Riven. While I was reading that page, I noticed that Riot had the model and everything all ready to go, so why not revisit it? I would love to play as him, I could easily see him being a stealth champion, perhaps when he hugs walls he turns invisible for 3 seconds and remains invisible as long as he's hugging the wall? And before people say he was reworked into Kha'Zix or something like that, I read on the wiki that: "It was initially speculated that Omen could have been replaced by Kha'Zix. Morello has stated that Kha'Zix has nothing to do with Omen. [5]" So why not revisit him. Riot already has the model done, perhaps do a few changes and Omen will be good to go. I was also reading up on Lee Sin, and I found out that he was originally cancelled but brought back through the community wanting him. So, Lets all show some support for Omen and perhaps bring him back? I feel there is a lot of potential out there for him.

For any of you looking for the Wiki Page for Omen, here it is: http://leagueoflegends.wikia.com/wiki/Omen