in the climate which I live (Philly area), every type has it's place. I have about 20 +/- kilts.

In winter, the 8 yard wool is most comfortable.
In spring / fall, the 5 yard wool and Semi Trad PV are more comfortable.
In Summer, the Casual and my FKs are great as well as the Semi Trad and 5 yard wools.

If you're in a "colder region", then I can completely understand the 8 yarders being the kilt of choice. If you lived in a HOTTER region (FL, CA, TX), then the Casual/semi Trad would probably be the all round kilt of choice.