The problem with Mir, Unity and all the convergence ideas was that they were poorly communicated.
They didn't really engage with the community and kept all the discussions and development behind closed doors, releasing dumps of code once in a while once they reached a milestone that they were satisfied with.
That's what Google does with Android, for example, and that would be okay... but only if they were able to take on such ambitious plans.
You can't expect the community to welcome you when you blindly follow your ideas and you can't even produce anything in quality. And when I mean in quality, I mean something that justifies going your own way, not just another "GNOME clone" without any added features.
I'm pretty sure they had amazing ideias in mind and that they had reasons on why they avoided going to Wayland but... is anyone able to point out any public mailing list, or public blog discussions, where they discuss all of this? I really tried to follow all Ubuntu/Mir/Unity/Phone/Convergence project but all the information I found was poor and outdated. Even working Ubuntu Phone images for the Nexus 5 was hard to find.