...I honestly don't see how you can say using a tree is more efficient... et al
TCs "no hierarchy" and keyboard-shorts methodology works fine if you already know where you are going... but if you don't know exactly, then a tree lets you see the "big picture".
Maybe some of you can keep your entire file hierarchies in your heads and you always know exactly where everything is. In such a case, pressing a key a predetermined number of times always takes you exactly where you want to go, right?. Good for you!
For the rest of us (for instance, I have over 500Gb of
personal disk space on six physical drives + eight virtual drives with over a million files and folders, growing daily), any actual copy/move episode is preceded by a (sometimes short, sometimes longer) period of thought, research, and decision because I can't (and have no interest in) keeping all of it at the forefront of my mind.
Even if it sucks as an interface for actual file activities such as copying, a tree is a good
visual overview for a hierarchical file system. It facilitates the "decision" part of a file activity.
When designing user interfaces, it is important to understand and implement for ALL components of a task. The actual navigating/copying/moving are only the endpoint of a file system task. First you have to understand, decide, locate, select, etc.
TC needs more and better visual tools for that and an optional folder tree in each panel would be a good step.
(Sorry this post is "all over the map" but most of this stuff is closely inter-related.)
I have to agree with Alya in some points.
(The tree's fully expanded, however. I'll work on that. 
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