Capability and usability aren't entirely unrelated. Applications with limited capability have no need to distinguish between initial usability and advanced usability. Applications with lots of capability must make tradeoffs, as ease of use and learnability aren't merely measures of the initial experience.
Emacs is easy to use and easy to learn, once you learn some of its basic quirks.
It's easy to use:
To start emacs, just type emacs. To open a file, type C-x f, then the path to the file (you can use tab-complete to enter the path). This automatically opens the file in a new buffer. You can open as many files as you like, and switch between the buffers with C-x b. To split the screen and see two buffers at once, you can use C-x 2 or C-x 3 depending on whether you want them aligned vertically or horizontally. Text entry and basic editing use most of the same conventions as the unix command line. C-a to go to the beginning of a line, C-e to go to the end, C-k to kill, C-y to yank. C-s forward-searches for a word. C-s again searches for the next instances.
Emacs is easy to learn:
To get a list of keybindings, such as the ones I mentioned above, type C-h b. This presents a list of hotkeys mapped to functions. The function names are descriptive. To get a more detailed description of any function in the list, simply put the cursor over the function name and hit enter. Press q to go back to your buffer.
Navigating the buffers can get complicated sometimes, and the function names can be archaic and definitely take some getting used to. There's also a lot of information available and it can be challenging to sort through it. But, all that information IS available and usually easy to get. That makes it easier to learn in the long run.
Also, to address your example, you don't need to know emacs-lisp to start appreciating its capability, and once you do start customizing basic configuration it's not too much more difficult than any other configuration language. From my .emacs, for example:
(global-set-key "\M-[" 'start-kbd-macro)
(global-set-key "\M-]" 'end-kbd-macro)
(global-set-key "\C-b" 'switch-to-buffer)
It's very straightforward, once you know what "\M" and "\C" mean. At first, you don't really need to know what the single quote means, just that it's necessary. For something less intuitive:
(setq inhibit-splash-screen t)
It's still pretty clear what that does.