Honestly - Toa Codex aside - it doesn’t seem like Toa of Ice would actually need a team to defeat most opponents:
I just imagine Tahu and Co giving everything they have to no avail and then Kopaka rolles his eyes, raises a hand, and the enemy simply blows up. 
Wouldn’t a large body combined with some kind of isolating material be better in terms of heat conservation than a short one?
A large body could store more heat, yes. However, a shape’s intrinsic ability to hold heat is dependent on the ratio between its volume over its surface area; the higher this ratio, the more heat the shape can easily hold. The shape with the absolute highest ratio in this regard is the sphere, so the closer a body is shaped to a sphere, the more heat it can hold. To this end, limbs are actually terrible at storing heat as they’re relatively long, thin cylinders, which are intrinsically poor at maintaining heat compared to the core body, which is much wider without being much longer. So yes, a body that is large in volume would be better at storing heat, but making it taller alone isn’t going to help much because that also lengthens the limbs; to at least keep them neutral by comparison, you’d have to make the arms and legs a lot thicker too, which will eventually start to impede their mobility (or in set form, their posability). So, to keep the Matoran and Toa of Ice from looking ridiculously large compared to their compatriots, I figured it would be better to keep them kind of short and stocky instead.
Insulation can of course multiply effective heat storage greatly, but that’s an independent factor and one that I’m sure is well incorporated into the Ko-Matoran design; the stocky appearance is probably due to extra insulation built in.
I added a picture to illustrate my idea for an Air color scheme:
Also in the document.
I dunno… Kinda looks as if he’s wearing a dress under his armor to me.
I can see how this benefits camouflage, but it just looks ridiculous otherwise in my opinion.
Wait you can draw too? Is there anything you can’t do Scorp?
Yeah, salmon pink is unique but not the most appealing color…
Sports.
I meant something that mattered 
Planning my life. I’m three months out from graduating college and still don’t have a clue what I’m going/wanting to do.
I’ll tell you a secret: none of us do…