So right now most players despise having death rained on them from a tank they can't fight back against.
My idea for fixing this is fairly simple. Currently it's rare to see counter battery fire and as a result, at the end of a game that started with 3 Arty a team, it'll still be 3 arty per team alive.
If the rewards for counter battery were improved, this would really help it as it would:
A) take Arty attention away from normal tanks at least partially at the start of a game
B) mean Arty dies fairly fast so there are functionally fewer in each game
C) mean that arty has to move in between shots and as such spends longer between shots.
They could do this by adding in a medal for killing an Arty that wasn't spotted at time of death or something along those lines that gives you say 250 XP per arty kill.
This makes it worth it for artillery, as they are getting bonus exp, and it helps standard players as it lowers the overall effectiveness of artillery.