Look, historically defensive technology and offensive technology have always gone back and forth as to which of them is more advanced. In the middle ages, it was defensive technology of walls and armor. Then offensive technology (guns) made that obsolete. Then well designed forts made defensive tech superior again, but even better artillery made this not the case anymore. Then tanks made defensive tech supreme for a short while. Now they aren't anymore because of weapons that can punch right into them.
But bunker tech is advancing very well these days, and modern IADS can make offensive air campaigns very difficult to pull off. Materials science might make some leap that allows some new form of armored vehicle to take point again. Or maybe it'll be spec-ops in power armor for localized superiority (getting in and out before heavy weapons can be brought to bear on them).
Don't cry over it, watch with joy for defensive tech to make some big, awesome, comeback. It's the way of war.
