Of course a Big Ten, 0 or 1 loss Nebraska makes the playoff. However, Nebraska has had 25 seasons with 0 or 1 losses, with 14 of them coming before 1962 (including the 1890 Nebraska Old Gold Knights, who went 2-0 under legendary coach Langdon Frothingham). That's 127 seasons, or roughly a 20% probability of Nebraska having 0 or 1 loss, if you want to weigh every season the same. Now, they'll be 130 FBS teams by next year, with 4 making the playoff, which gives us a 3% probability of inclusion, but a 25% probability of winning. Now, if somebody who is smarter in math than I am would check this, I would appreciate it (my brain doesn't start working again until next week), but I think that give a probability of both events occurring somewhere in the vicinity of 0.6%.
Now, let's expand the playoff to 8 teams. This gives us roughly a 6.2% probability of making the playoff, but a 12.5% probability of winning. The overall probability of both that and Nebraska losing only 0-1 games is roughly 1.2%, or about double what it would be under the current format. Again, if someone wants to check my maths, I would appreciate it.
The point of all of this is that, yes, it would be more difficult for Nebraska to win a National Championship under an 8 team format. However, the probability of Nebraska having a 0 or 1 loss team is not that high (the probability is certainly lower due to the difficultly level of today's college football compared to the past, but there's no way in hell I'm working with weighted averages right now), which means it's a far better proposition to minimize your margin of error and maximize your chances of getting into the playoff. That's the point that a majority of posters in this thread that are in favor of an expanded playoff have been making: not only is it more fair, and more college football, it gives Nebraska many more opportunities to be able to win a National Title.