The problem isn't complexity, IMO.
I mean ink and paper are actually shockingly complex things, but the 'interface' of 'writing on paper' has been relatively standardized in the collective human mind at this point -- but that's still pretty recent. The evolution of pens, of water-soluble ink, of papers made with varying materials and thicknesses and purposes, etc. It took a long damn time.
So computer interface use may not be 'standardized' for a much longer while yet. :\