Allow me the indulgence of a personal essay on this topic. In my many years of teaching and consulting I have found that people vary widely as to their taste and ability for memorizing keystrokes.
At the other extreme are the many people who mostly just use the mouse along with the standard well-known command-key shortcuts., as is the intention for WYSIWYG GUIs. One of the biggest differences among people is the extent to which they use the mouse or the keyboard for navigating among characters, words, lines, paragraphs, and pages, including selection and selection extension.
I am on the keystroke extreme: I have keystrokes bound to "activate application" for dozens of applications. I have many groups of macros bound to keystrokes that are only active for one application. I use keystrokes for editing, for automating, for file manipulation, window manipulation, and on and on. I know hundreds of Emacs keybindings, and many more that I know are there and can find with an "apropos" lookup. It is a wonder my hands haven't fallen off by now.
And I have been using a mouse since 1975. That is not a typo. I was at Xerox PARC when the Alto, the precursor to the Mac, was invented and used. So my preferences for keystrokes are not out of a lack of mousing fluency.
Of course KM is drug, wine, and food for me. I used to use QuicKeys, and a succession of similar utilities before that. I used Launcher and Butler (QuickSilver and Alfred were also options). KM is 10X more powerful, better designed, and complete then all the rest of those combined.
And remember, the ability to bind a key is just a small part of the game — being able to program your own tiny applications, automate frequent sequences of actions, write scripts, etc. opens up OS X and system and applications to however much effort you want to put into changing its behavior. People vary there too, from those who aren't at all interested to the extremes you see on this forum (or in my case, don't see because I don't post much of my own work). I will program and automate anything that has any kind of programmable interface. (I have written hundreds of macros for Emacs, my favorite programmable environment. I have automated MS junk with Visual Basic, ugh. And so on.)
Palettes are an excellent compromise, as suggested above — you get to script and automate anything you want, but give yourself a visual interface to it. Take a look at my palette for revealing Safari pages from a selected site.