I definitely don't get it either. I usually vape at ~6 to 7 watts with ~2 to 2.5 ohm coil. When I wrap my coils, I figure out what resistance to make it first and then cut off the appropriate length of kanthal. I've pretty much go it down to a science and very seldom have excess wire that gets wasted. Sure, with the sub ohm coils you can get great, fast heat, but I've found that the wick and coil needs more frequent cleaning and that it's much easier to burn juice. Too, battery life in the sub ohm range probably is not very good.
To me, sub ohm vaping is like the guys with the big block motors. The power is there and it's fun to use every now and then, but when you do, your gas mileage drops exponentially, just like vaping sub ohm causes your battery life to drop.
I'll stick with my 2.4ohm twisted 30 gauge kanthal in my KFL, Taifun and Aqua's running at 6 watts.

