For people who are apparently enlightened enough to realize that no calendar, however rational and perfect, will be accepted if it violates a certain religious rule (the sabbath), they are apparently quite ignorant in their advocacy of UTC for all purposes.

It's all well and good to eliminate time zones as such and have each region operate on a fixed clock, but to suggest that people will simply stop paying attention to the sun is insane. If you want wide adoption you can't expect people to make radical change in their lives. Most people prefer to wake with the sun and sleep when it's dark; some studies suggest that we are biologically predisposed to want or need this. Whether it's 05:00 when I wake or 16:00 when I wake is immaterial to me (that's just a number, just what you call it) but whether it's daylight when I'm out and about just plain matters.

In effect you'll probably always need a way to divide the world by when the sun is up, even if the clock doesn't change.