The Zags were a #1 seed last year, even though their only 2 losses were to the only Top 20 teams they played, Illinois and Butler, both #13 at the time. Ironically, they were beaten in the second round by - Wichita State. So, yeah, if the Shockers were undefeated, I think they would get a #1. But they would have to beat out all but three of (likely):
Arizona/Oregon (Pac 12)
Syr/Duke/UNC (ACC)
UK/Florida (SEC)
KU/Okla St/Baylor (Big 12)
Wisconsin/Michigan/Ohio State (Big Ten)
Villanova (Big East)
If each of these conferences had a team that did very well during the regular season and won their conference tourney, seedings would get very interesting.
Undefeated no doubt they get a #1 IMO. BCS teams with 5 losses will be fighting for 1 seeds.
As for the bolded point, this is not the way the committee looks at it. Where Kansas St and Oklahoma St were ranked at the time they played them is totally irrelevant to the committee. Kansas St was a 4 seed, and Oklahoma St is a 5 seed (who they beat on the road). Those are two top 20 wins (based on seeds), including one on the road. So indeed they had two top 20 wins.
Wichita St will not be able to match Gonzaga's level of wins, even with the quality win at St Louis . They don't have stuff to match Kansas and Oklahoma St in OOC play. And with the MVC not appearing to have a top 50 #2 team it reduced quality wins in conferences. Gonzaga was able to get road wins at St. Mary's and BYU (a very tough place to play) which are notable.
The comparison to Gonzaga gets interesting though if they have 1 or 2 losses. Lower win profile, and worse overall losses (if they reach 2) but the big eye test factor of last year really changes things positively for Wichita St.
The other consideration is power ranking. Gonzaga was #5, Wichita St is currently #16 in KP. Big difference. No doubt in my mind some committee members consider that especially for non BCS Schools who simply cant match schedules. The eye test is basically any other crap the committee member wants to use - if a committee member believes in power rankings (and some do in order to try to equalize with BCS) they may just say Wichita St is just not dominant enough.