If you watch enough football you see a draw called on 3rd and long all the time in the NFL. There are a lot of reasons. The defense will be looking pass, linebackers will be pass blitzing or dropping back into coverage, so you could catch them off guard for a 10+ yard gain, especially up the middle if you try to clear it out with your routes. You have a short field and not much space to work with vs. their pass defense, as well, and they are a defense that usually thrives off of turnover, so the chances of something bad happening are higher. The main reason though, is risk vs. benefit in that situation, up by 10 in the 2nd half. If there is absolutely nowhere to go, and Rodgers gets creamed after holding it a split second too long, or there is a pick 6, we're all freaking out.
I didn't necessarily agree with it, but I'm sure they know what they are doing, and saw something that said they should run it. This is doubly the case if there was a run/pass option and Rodgers also went with the draw play.