There is a reason they order sales by: season tickets, then mini plans, and lastly single games.... It's because they know some people will pay full price for tickets to games they don't want in order to get tickets to other games that they do want.

Anyone that wants to go to these lightly attended December games can already do so for less than face value. For the St Francis game, there were lots of $6 tickets on StubHub ($10 with fees) and $10 family 4-packs through the ticket office. Meanwhile I paid $20 for my season ticket. And there were still tickets available through the ticket office at tipoff. The fact that a Saturday game wasn't sold out at a $10 price point (and that $10 not only got you a ticket but also a drink and a hot dog) points pretty directly at a demand issue.

I think your a la carte idea would be successful in filling in more of the lower row seats but it would come at the expense of a fair amount of revenue.