Nebraska played a home and away series with Notre Dame in 2000-2001, I thought it was more recent than that as I was at the game, and it doesn't seem like it was that long ago (that must mean I am getting old

) They also played Arizona St. the following year (one of your bold teams.) I also think it is odd to include Colorado St. as a "bold" team, but not include Pitt or Southern Miss... both very similar in calibur.
Ok.. two thing that are facts. Colorado has scheduled some tough pre-conferance opponents..... Nebraska has started to schedule tougher opponents the past few years.
I think there are a few reasons for this....
Over the past 15-20 years Colorado has had a lot less to lose, and a lot more to gain by scheduling tougher teams. This is not a slam on the Colorado program, because that is the right way to develop a contender. Nebraska on the other hand had a whole lot to lose..... an early season miscue could mean the difference between a National Title or not. It's not a situation exclusive to Nebraska either... most top teams in top conferances have done the same. As a fan, I didn't necessarily agree with the approach... especially during the "glory year" when I wanted to see them beat all comers.
The fact that Nebraska is starting to schedule a lot tougher pre-conferance games says a lot about where the program is now. We are no longer on the top of the college football world trying to maintain that perfect record every year. A close game at USC this year will be a big boost to the program, even if it ends up as a loss. In a way we are where Colorado was in the early 90's... but with a lot better facilties and more booster money.