I really disagree about area mines. It takes 3-4 layers of mines to destroy an entire wave of tech 2 ships(in most cases) Which can take anywhere from 55, to 80 mines. At 400?/800 a pop, that means for each wave destroyed, you spent 22000/44000 - 32000/64000. For that many resources, you could easily create a large enough sized turret defense to take out the wave. 220 - 320 mk 1 basic turrets, or 110-160 mk 1 MLRS turrets.
You also have to consider the cost of maintaining the minefield when there is no incoming wave. Random groups of 10 ships will take out 5-10 mines which just wastes resources.
I will agree that before the damage nerf, area mines just slaughtered everything, but now they feel about right atm.