Many of them are too big to deploy. Unless you are fighting on a homeland, it's too big to get to the fight via normal methods of transportation.
Some of the towering ones would be missile magnets. Such a giant vehicle would be targeted from miles away by ground and air launched anti-tank guided missiles.
Lots of close up defensive guns. Most tankers like to engage and destroy the enemy from the maximum range possible. Seems like they were designed to fight enemy heavy armor, but have a lot of firepower to defeat close in infantry support.
And shot traps, lots of shot traps on many designs.
Great stuff though. I admire their work.