I don't necessarily disagree about playing it safe (although when Fleck has done that he has been ripped apart here for it). But given the timeout and clock situation I can see why they tried to get the game winning field goal in regulation as opposed to play for overtime.
They ran on first down and got good yardage which is why they decided to throw on the next play. Had they been stuffed on first down they probably just let the clock run out. Can pretty much guarantee a play for a safe throw of some kind was called on the next play, but Aller got pressured so he panicked and made a terrible decision to throw the ball into a major danger zone over the middle of the field as opposed to taking a sack or throwing it away.
The strategy decision to try and win the game in regulation is on the coaches. The pick is on Aller because he definitely was not coached to make the throw he made.