Windows Phone has always been super minimalistic - mainly text on a solid background with images here and there all wrapped up in an efficient pivot. Perhaps they simply aren't used to working with a more "complex" UI on handsets. I'm not sure what it is, but something is very wrong.
I use Android and iOS extensively, and I used to use WP8.1 extensively. I still use WP8.1/W10M some, but WP is no longer my primary device.
Being quite familiar with all three OS's, here's my take concerning the minimalistic UI: it was great, but it was too simple as features were added. WP was originally minimalistic in feature & capabilities. As features were added, the UI could not remain simple. As a result, the UI designed for simplicity became quite complicated to use. I mean, it looked great, but I found that when I started using it, it soon became apparent that it was convoluted (Settings menu anyone?).
I found myself doing a lot of swiping and tapping compared to performing similar tasks on iOS and Android. WP had too many features for a UI designed to be simple. It reminded me of a quote I read somewhere (I cannot find it at the moment, but this is the gist of it), "
From over simplicity comes great complexity."
While icon filled screens are not as pretty as tiles, I believe that there is a reason Microsoft has used icons in Windows since Windows 2.0, released in 1987, and has returned Windows to primarily that after trying to push tiles in Windows 8/8.1. It would probably be the same reason that iOS and Android use icons. Icons are what seem to work in our current paradigm. Microsoft appears to have no plans to abandon icons in Windows anytime soon.
Maybe the rejection of tiles by consumers in Windows 8/8.1 and on WP is because we do not want to change. We as humans tend to feel most comfortable following tradition. OTOH, we are also very adaptable if something better comes along. I believe that if Live Tiles actually worked better, they would have been embraced by consumers.