It doesn't look pleated in the back ... I would think this should be a key defining variable in what makes a kilt...

It's *wrap* which is the family the kilt is also of.

Tons of peoples around the world had (and still have) knee-length (or a bit less or even more ... but knee-length and less implies ability to be unencumbered in mobility) wraps for men as the norm for most of human history (probably starting with some animal skin tied at the waist). I feel it is really neat walking around today wearing a clothing based on this ancient primary simple form of clothing idea .