This reminds me of a fight in a church about how high on the wall the cross should be hanging.
Bitter arguments among side-stream groups (church-goers, linux-users) are a much bigger reason why these groups do not attract mainstream audiences then what it is they're fighting about.
Unity, Gnome, and KDE are all headed towards a more Mac-like UI because Apple is the most lauded software design company in the world.
Like church-goers, Linux users should be supporting and celebrating innovation in design that are meant to increase use in the software. If such innovation was more broadly celebrated for its own sake, then it is much more likely that one of the major players would be willing to risk new design decisions - to really experiment with the UI. Instead, the same changes are all adopted by the major players because trying something too different will get your ridiculed, and that leads to losing early adopters, and that leads to a diminishing user base.
If you want to see Linux become more mainstream so that a generation of computer users can have a little more software freedom, then join the discussion by celebrating experimentation instead of condemning it.