Personally I think that arty as it is right now in game is very broken. I think that it is overpowered in the sense that everyone can use it and it is very cheap for the damage it causes. It is very difficult to destroy because it is on the opposite side of the map. For example if you are being hit by an artillery strike with all 3 guns going you probably would want to stop them from slaughtering you but, if you try to stop them you can go back and kill them but obviously not spawn camp them. There is nothing stopping the enemy from 30 seconds after you leave from getting back onto the guns.
My proposition is to add a Hummel and a Priest. They are mobile artillery guns and I think they would make the game more fun for everybody. If they do add these I think that they would significantly reduce the range of the guns to balance them. You would be forced to be close to the enemy but not too close, it would add a whole new aspect to tanking as it is right now. This would also give an incentive to change how expensive it is to spawn a tank and the commander would have to decide what type of tanks he wants if he wants medium range artillery or having a Sherman up close to the enemy supporting the infantry. This could possibly also give the Germans a little advantage because the gun of the Hummel is a lot bigger the Germans need every advantage they can get because statistically they loose almost every game.
Hummel:

Priest:

I definitely agree with this, arty is just so far out of the way that if the enemy is on an offensive and you're getting pounded by 3 guns, they are so out of the way that by the time you get back to them then they could possibly hold your team off and effectively cap. i do think mobile arty would be much better and take out the extreme accuracy and ability to just hop right back on that is in the game now.
Solid idea Zach, outside the box! Artillery is entirely too accurate in my opinion and any level of nerf that could be placed I think a lot of players would appreciate. The cost should go up, take an accuracy hit, and make it a squad. Then people can prepare for it and send units to deal with it ahead of time making it a bit more difficult to use.
Would this add a slot to the armor slots per map, or would it just be an option for the tank slots that the maps currently have? I think it is a pretty decent idea, aside from adding these, another way could be to make arty slots and only allow 2 per arty squad, similar to the way scout teams work...where the loader cannot fire the gun.