You can rush the Bofors and burn it down with Volksgrens now, it's not hard, hell even before you could just shoot it with AT guns or Raketenwerfers. I rarely even built it before but now rarely is going to be never. It could at least be good at shooting down planes but it can't even do that (never could really).
Try putting something between your bofors and the enemy it's there to help your army not be it.
A vickers, some Tommies... If the enemy is walking right up to your emplacements unopposed what you need for it to be "good" is not something that is balanced or fun. If the enemy is just plinking away with raks DO SOMETHING about it. It's got more health than a tank, it doesn't just disappear in a blink.