It seems like Fire primarily ended up getting healer stuff because they already had Absorb Heat assets from previous devs. I know this because I suggested a power very similar to it, and then when it got put in the game I thought it was cause of my suggestion, but Kaizerin rushed in to completely smash those hopes and told me the power was already in the game but not implemented.
So I dunno, let's have some comic book logic fun. At Kiga, why fire is healing you is obvious... like that's too easy, so Kiga-based explanations are disallowed o3o ( I can't enforce this though so feel free to make me look dumb by giving a Kiga-based reasoning ).
Okay let's see if this works. Because he seems to know a lot of things I am going to attempt to summon @jonsills
. Also because he gave a really good answer to my wind question, I am going to attempt to summon @bulgarex
My best guess is that it has something do with how heat causes biological functions to happen more rapidly. I think. Like I dunno... I think that's a thing I heard one time? Maybe?