To be fair... removing it is not as simple either. As there as many that likes to play them and has invested time in the lines as there are people that hate them. So removing it and giving a compensation might lose them as much players as keeping it. Or even more then if they added more lines. Who knows.
Either way, there is no "easy" fix for this as most thing regardless. As most that say the easy fix is to simply remove it, only see it from one aspect. WG don't. As they have more than one type of player to keep happy and keep playing.
And if arty was gone. A new class would take the hate and cause a similar level of toxicity. Tho on a lesser scale. I've seen it before when Dice did try to remove and fix the snipers on Bad company on one of their updates. As they were hated as much on their forum back in the day as arty is here. The MG medic and support class with mortars took the heat next and created as may rage topics, plus all the rage from the snipers that lost their class at the same time. So after less then a week Dice just tossed in the towel and add said "F it" and added it all back and pulled the update for PS3 before it was added there.