I want my grandma to not have to relearn to yet another UI every two years. Canonical has commited to support the LTS releases for half a decade, which, while not coparable to XP, is for older folks still a better bet than anything the mobile world has to offer.
> I want my grandma to not have to relearn to yet another UI every two years.
Those two statements have little to do with each other. The current (and upcoming) version of iOS still works largely the same way as iPhone OS did 6 years a go.
Modern mobile OSes are easier to learn than desktop OSes and are less encumbered by malware. For someone who has never used a desktop computer or the Internet, starting off with a good tablet instead of a personal computer is a better choice.
Still, in the tech world, half a decade is pretty close to eternity anyway. XP sure had a long life.
Elderly people suffer from planned obsolescence, too.
If you do actual research on older computer users, you'll see that many prefer a desktop environment for the sole reason that they can get a monster monitor.
"But my Grandma!" you might say, and you might be right.
But expand your dataset and you'll start to understand why desktops and iMacs haven't become obsolete.
http://en.wikipedia.org/wiki/Population_Growth_of_Munich#Age...