From a gaming perspective, I think that the giant robots are being introduced to give armies a unit that, essentially, cannot be killed. Well, can't be killed without your opponent sinking an obscene amount of firepower into it. Tanks die to melta, lances, etc no matter how good they are. Infantry gets splattered. The difficulty of doing so many wounds to such a high toughness creature, though, often through and invuln and/or a good armor save, is very high.
An Iyanden army with a few spirit seers that rolls 2 renews and has the ghost helm of whatever can heal 3 wounds on a Wraithknight per turn, essentially letting the Knight--who can't afford to be ignored--essentially tank the majority of the enemy shooting. 2 Riptides with a bucketload of T6 2+ save wounds? Good luck killing those in a points-efficient manner, while they can make their points back in a turn blasting some tank or unit into oblivion. So on for Dreadknights, Trygons, etc. that's why the Titan of a Wraithknight isn't a vehicle but is a monstrous creature instead: durability.
What sphinx of plascrete and adamantium bashed open their skulls and ate up their brains and imagination? Imperator! Imperator!
Last edited by Mossy Toes; 09-10-13 at 04:43 PM.