>The AI can't figure out that if it wants to shoot the tower it needs to move so the level geometry is out of the way
I understand a REAL AI fix would cost a lot of money, but is it really hard to put in some code that does
//if obstructed
run figure out nearest firing position.function
return (position should move to)
move to position should move to

Like I know it's more lines of code than that in reality (probably a hundred or so), but they've had years to fix this shit.