My guess is that twisted
coils offer a greater surface area than a comparably sized single wire. It provides more nooks and crannies for
juice to cover and get vaporized.
Micro coils concentrate the heat over a smaller area than a "normal" evenly spaced coil. A twisted micro coil concentrates even more heat in that small area, providing a nice warm vape with a satisfying throat hit even at low nicotine levels.
I personally do not sub-ohm, as I get clouds of warm vapor and great throat hit from a simple micro coil and cotton at 1.3-1.7 ohms.
The above is, of course, only my humble opinion. I do not claim it to be fact, only know that it works for me.