It is not cool, it is ergonomic. Kinetic makes very easy and efficient to move through a page bigger than the screen, by using a very natural hand/wrist movement.
Methods like pushing buttons on those tiny devices force the fingers to adopt non natural positions or angles while applying force, which in turn causes tendon strain, and pain in the end.
Non kinetic scrolling with the stylus like microb is very suboptimal, since moving through a big page takes a very long number of strokes (and microb scrolling responsivity is far from good). It also implies some tendon stress, since those prolonged strokes are done with more strength than quick strokes, and more strength is required to grip the device.
Finally, kinetic scrolling allows more feedback because the user sees a continuous flow of the page, with a speed response similar to what is expected in the "physical" world (that is why it seems "cool")