We've had multiple TPKs/near TPKs. Kaiju might aggro the strongest offensive unit, but that doesn't mean they never attack the lower power units. Namely when everything tougher dies. Most of our missions are effectively on a clock where we just need to hold the kaiju off, so having our last line of defense be our strongest defensively is plenty logical.
Bolded part isn't true at all. We've had
one mission that was on a timer, and it was very much a special case, considering New York is the richest city in the world, and is a part of the most militarily powerful nation in the world. Most of our missions either end with the Kaiju dying, with the speed of the kill determining how much damage is done to the city before its death, or they end with
us dying, and then the Kaiju maybe-maybe not getting to destroy the entire city, depending on how the local military responds.
Beyond that, no, this doesn't make sense. We are always limited in how much value in terms of units that we can field, both in an obvious metric (cost of those units), and a non-obvious metric (research time dedicated to improving those units). If we spend some of that value--be it cost or research time--on tougher units, then we
aren't spending it on more damage. Thus, we want to maximize our gains from any toughness buffs, because unlike damage, they aren't constantly being used regardless of the unit.
Indeed, toughness that isn't actually touched is
useless, because it does not affect the outcome of the battle. If you spend 500 on making your DPS units tougher, and none of them die (or, as seems somewhat likely, they all get oneshot anyway), then you effectively gained nothing from spending that money, when you would have definitely gained
something from spending 500 on better damage--likely a faster kill, which means less city destruction, which means better pay.
And less kaiju attacks suffered, for us. More damage is
always good, you can't have too much damage.
Anyway. The reason why I still recommend creating a heavily armored tank unit is that armor is disproportionately valuable the
earlier it is used. Essentially, every unit deals its damage every round. Every unit lost is a reduction to the amount of damage we're dealing. Consider if we have, say, five units that all deal 1 point of damage every round, but four of them die in one hit while the fifth, who is always targeted first, dies in
five hits. They'll deal 5*5+4+3+2+1=30 points of damage, and die after sustaining nine hits. If instead we had five units that deal one damage, and each take two hits to kill, then we'll instead dead 5+5+4+4+3+3+2+2+1+1= 30 points of damage, and die after sustaining ten hits. So they have more overall HP, but deal less damage over a longer period of time, and take more significant losses if the Kaiju only needs, say, 18 damage dealt to it. And all that, despite probably costing more, because
every unit is a buffed design, rather than a singular buffed design and a gaggle of cheap units.
This all being said, it
is reliant on my understanding of Kaiju prioritizing the most damaging units. I think I have a fairly decent base for this, considering I did do a detailed examination of several Kaiju fights--but I haven't analyzed the last couple, which could have more information that contradicts my previous hypothesis. If you want to read over them and try and figure out if there's any other patterns to how the Kaiju attacks, that would be totally awesome and could prove me completely wrong.
If we really want to, we could come up with some way to aggro the kaiju (ex pheromones from parts, irritating sonic/chemical weapons, or just a bunch of flashing lights)...though I doubt infantry would be the ideal placement for such tools.
These are all awesome ideas which I fully support. I'll happily throw kaiju bits at you, if you want to use them to develop such a thing. Free of charge.