If I were Oregon and Washington, I'd stay in he PAC for now. Much easier road to the playoffs.
As a fan of sports you are absolutely correct. However sports competition and post season paths do not dictate what school goes to what conference.
Realignment is fully driven by the almighty dollar. If it were about the easiest path to the playoffs OU, Texa$$, UCLA, and USC would all still be in their respective conferences. The fact of the matter is OU, Texa$$, and the SEC and UCLA, USC, and the B1G all thought it financial beneficial to team up.
This will be the same case for Oregon and Washington. If they find a conference who they feel would be financially beneficial and that conference agrees then that's where they'll be. As it stands it would appear they are holding out for the B1G because the schools see them as financially beneficial to them. I'm not sure the B1G shares that sentiment. Likewise with the Big 12. I think the Big 12 sees Oregon and Washington financially beneficial but I don't think the schools see it as an upgrade from the PAC. So they'll wait until they get a call from B1G or they get the full bid from the PAC. If that bid comes in to low then they may just bite the bullet and jump to the B12.