That's the strange, mystical device that seems too complicated for many so-called "drivers"...
Courtesy on the road is part of being a good driver. In other words, not using them = suck. Sure, driving skill is important, especially for those of us that push our cars, but it's only part of the package.
In other words, use 'em, or take the bus.
If everyone used them, I can see only one downside; body shops & gun retailers could lose sales.