Mobility and possibility to use large number of construction bots.
Yes, but it should be a good tool to be a good tool. Biter bases are quite large even at default settings at that phase of the game and if you need 3 cannon shots to kill one base (because they heal between rounds around), it is far from good. Maybe you think conquering of single nearby iron deposit, but I think railworlds which need huge areas effectively conquered. I agree nerfing of machine gun (even real 12.7 mm tank machine guns have very much more than double "dps" compared to submachine guns) if they double (or triple) cannon power to be one shot one kill against nests. Explosive rounds should kill or damage couple of nearby biters too to be worth of investment.I think the tank should remain the good mid-game tool to fight biters it already is, creating a bridge between the times when you can fight biters on foot or with a car and the times you need artillery/nukes/power armor stuffed with shields and exosqueletons.