Unity was never the main reason people chose to use Ubuntu -- it was always (well, from when I first heard about it until I lost interest (5 years ago)) the claim that Ubuntu is easier to install than Debian. I never understood the fixation about ease of installing , as that's something I either did once every few years on custom hardware, or had automated already using a CFM. For stuff I installed manually (laptops,…
For people who have little / no experience with Linux, an easy low-expertise required install makes all the difference.
Installing Linux used to be a huge problem, and that's why Ubuntu became popular. Other distros caught up, but it was really Ubuntu that pushed it.