The biggest play on that drive was that Nebraska should have been called for PI against Eric Carter in the endzone. Their DB ran into him and never turned his head.
At the time of the FG, we were down 38-22 and it was 4th and 15. The chances of us converting 4th and 15, scoring a TD, getting the 2 pt conversion, scoring another TD, and getting a 2nd 2 pt conversion are what? By kicking the FG, it would have at least allowed us to win if (big If) we scored 2 TDs.
If we kicked the FG on 4th and 5 I would have been pissed. Not so much on 4th and 15.