So I have a Theory regarding Kul'Tirans and Drust and why some of the population is so stout other than them just being acclimatized to a harsher environment.
What if at some point the Drust and Humans cross-bred which resulted in these Bigger Humans? (8ft tall apparently since their models are taller than Draenei)
The only thing I have to go by honestly is concept art of the Drust Shaman which I think looks a little like the Kul'Tiran human model
Sadly I cannot post links and images at the moment or else I'd show the image. The image in question is on Wowpedia under the Drust entry if you'd like to check this out.
Of course as I said this is entirely a Theory but it would be neat if they weren't entirely human and would explain the Drust themed Druid forms they apparently have.
It's certainly possible, and would help make them a little more distinct from Humans. Plus it would help explain how they got their Druid forms. I hope it's the case.
From what I understand they were in conflict for a few years before they got wiped out but there were a few Drust who were tolerant of the human settlers.
"When the humans landed they tried peace but the drust went to war immediately, and only a few tolerated new neighbors."
Also I mean from a real life standpoint and a rather darker one raids do sometimes result in unwanted children ... especially when the attackers are barbarians but I doubt that Blizzard would take that particular route.
Maybe the Kul'tirans are just effected by the Drust's magic in the land... I mean it wouldn't be the first time that sources of magic = changes to physiology.
Also I think I put this in the wrong segment I seem to be delving more into -lore- here than general discussion my bad.