All pixelling is, is a manual manipulation of pixels for greater clarity, detail and composition.
I have a different opinion. Pixel art is not only technique (and as technique, it's not only the techniques that you mention here), it is also a separate art form, and as such has it's own history, aesthetic charge and future independent of current game art. Someone can be very clear and detailed and compositionally-sound with his pencil too, or in pure CG coloured artwork. The pixel-level control in pixel art IS formidable as a technique and artists that possess that sort of control will always be able to cram more
information into a piece of art, be it game art or art art than others that are more about general broad shapes and volumes. This isn't why pixel art is 'better' than anything else. Pixel art isn't better than anything else.
Pixel art is different from other types of art. The connection with the foundational, basic signifiers of machines: Binary, big, dogmatic squares, algorhythmic construction, fractal repetition, pixels as the atoms of presentation, the pure colors the computer screen tubes could first portray. RESTRICTIONS you are so hasty to brush off as mindless, scanlines, alternate resolutions and the concept of sprite (anima, soul, it is alive) over tile (static, dead, but with the benefit of repetition, depth and alteration) make pixel art so much more than 'manual manipulation of pixels for greater clarity, detail and composition'.