It makes total sense. You can't stay as sharp doing something part time compared to being immersed in it daily. Football players don't sit around during the offseason because there are no games. They take steps to improve themselves. It's a year round job even though there are only games 16 weeks a year. The refs should have that same type of dedication to their craft. Just like the players, the calls they make decide games.
If they had full time officials there would be no need to do things in the offseason for money. They'd have a regimented training program that kept them sharp. You wouldn't have mistakes made like in the Seahawks/Lions game with the batted ball.
Would it be perfect? Obviously not, but it would definitely be an improvement. You have a multi-billion dollar industry with players who makes tens of millions of dollars a year and the NFL can't pay the money to make the officiating as good as possible?