In his post-game interview, Brady said that the weather pretty much removed the deep ball and throwing to the sides for most of the game, leaving over the middle as the only real option.
Moss said pretty much the same thing; the weather conditions removed most of their options for passing for the majority of the game, but when there were breaks they tried to use the wind to their advantage.
If I were to hazard a guess, I think it was a combination of poor execution at times with heavy doses of uncooperative weather. If you remove the deep ball and sideline passing for most of the game, the defense is going to stop you over the middle. So, I don't think Brady played his best game ever, but I think weather was a huge factor. As for those open receivers, he probably saw them most of the time, but I'm guessing believed they would be risky throws to make with whatever the wind was doing at that particular time. It's hard to say without being on the field or in his shoes, but given his usual performance I give him the benefit of the doubt.
As for why he tried forcing the ball to Moss, I think he figured Moss had the best chance of coming up with a catch in those conditions, even deep. If you're going to go over the middle and they know you're going to go over the middle, don't try to throw quick passes with a wet ball near defenders hands. Instead, wait for the wind to work in your favor and then try to get it to the guy who comes up with freakishly good deep receptions when it counts.
In weather like that, remember that your primary goal, especially in the passing game, is to not turn the ball over. Even the running game was predicated on that -- straight punches up the middle. So while Brady didn't play superhumanly, it's unrealistic to expect 300 yards in the air, 2 or more TDs and no INTs in that weather.