The flaw with this argument is that it assumes that it is easy to hit an open 3 or that any college player should be expected to make 3's. By design, the guys shooting open 3's were 30% shooters. Theodore is .278 on the year. Karlis, who went 1-8 from 3, is .317 on the season. Cosby, who went 2-7, is .386. Even if you give Karlis 2 more makes to put him over his average and Cosby 1 more to put him right at his average, we win by double digits. The game plan was clearly to let them shoot because for the most part they are not good shooters. It was the same game plan last time around but they caught fire on their home court with a home crowd behind them.
Fuquan Edwin is shooting 3's at a .411 clip on the season and was only allowed to take one 3 today.
So while I see what you are saying, and at times it is hard to forget that this is not the NBA where it seems everyone hits every open 3, you have to take into account that there is a pretty good chance that it was the game plan to allow a collection of 30% shooters to take 3's rather than penetrate. Cosby is the only one that took a lot of shots that you could argue is a good shooter. I haven't rewatched the game so I couldn't tell you how many of his 5 misses were open versus contested but I can guarantee that Karlis took a bunch of open looks. And I think this was completely by design.