If you split end users into tech people and lay people, then I don't think it matters as much.

Most of my lay friends tend not to even realise they are not on the latest version. Their maps app gives them directions and the camera takes photos.

As for more techie people... that's why I much prefer Android. The ROM scene is amazing, and allows my original Samsung Galaxy S 1 to run the latest version of Android. I also get to experiment with different ROMs that take different approaches to mobile OSes.