Apps.
Perhaps with smartphones, the public has become acclimated to downloading within a closed environment as the source of their apps. This may help home users accept the repository-based delivery model on home computers too.
Jack, most of what you've said has been posted by your readers countless times over the years:
- word of mouth doesn't work on non-techies
- market penetration will increase when Linux is pre-installed by the hardware vendors
- the 'Wal-mart' desktop system (and Linux netbooks) disappointed consumers because they didn't understand what they were buying
- the public at large doesn't know Linux exists. I doubt many of those who recognize the name 'Android' understand it's a Linux-based OS (assuming they even know what an OS is). It sure isn't mentioned in the marketing campaigns.