To me both sorts of kilts look strange (the sort that's basically a saltire flag made into a kilt, and the sort which creates a saltire on your bum) because they're at odds with the way kilts traditionally have been: having a pattern that's horizonally & vertically oriented.

The kilts made out of any flag leave me cold, be it the Welsh flag, Union Jack, Cross of St George, or what have you.

Though there was a cool Japanese guy at one of our Games wearing The Kilt Of The Rising Sun (as he called it) which was, I must admit, very striking. (A white kilt with a large red circle appliqued on the front apron.)