(1) Linux didn't fail, the desktop is already a joy to use imho. It is just waiting till it reaches critical mass, then the Year of the Linux Desktop will be nigh.
1. I kid, I kid
I'd love to be able to run a mainline Linux kernel on a standard handset. It would enable a bunch of goofy things, like using old phones as IP wifi security cameras.
And that’s a problem that needs fixed. Out of any piece of software, the one that connects my hardware to my OS is probably one of the most important.
Although I find it dubious this alone is why Linux historically has failed at desktop. It certainly sucks to deal with, but at least people attempted to use Linux. Personally I would argue that people’s innate fear of change is the bigger problem, in my experience.