It's never been THE criteria...that's why there's been a committee, and not a BCS style selection. But it still is the most significant criterion used, and it takes A LOT to overcome a low RPI. Wins against Minnesota and Indiana might do it. Wins against Minnesota and Illinois will NOT...and that's assuming we take care of business against the scrubs and don't get tripped up against Nebraska or Ped State.
Why does everyone keep bringing Illinois up as an example of a quality win? They're sitting at 3-7 and 9th place in the conference, RIGHT NOW, and 3 of their remaining games are against ranked teams on the road. They are NOT a good team.
You can't discount who Illinois has beaten. They are a good team just inconsistent. IMO Illinois is neither a good win nor a bad loss in the big picture. In the short-term its a bad loss.