@tasket yeah, in this sense i suppose android is linux. But the design of that additional layer between OS and user does make a difference imho how attractive and useful to average user but also how enabling for app developers. You can have a "convergent" approach like #kdemobile or the browser as UI like #firefoxos etc.
All in all I have this vague feeling that there are enough pieces of the puzzle on the table that somebody could solve it but somehow it doesnt happen for years now.