Twenty five years ago, after five years of experience programming scientific applications (mostly math stuff, not much real programming beyond algorithms) I began a job programming business applications. At that time, there was very little general communal knowledge about very basic stuff we take for granted today like searching, sorting, memory allocation, data structures...
I began my collection with Knuth and another book (no longer in print) dedicated to data structures. These books defined me as a programmer. I learned MIX only because, as a programmer, I felt that I should be able to understand Knuth's abstraction. I admit that I was frustrated by having to do this. Ironically, even back then, the "other book" used, what was the de facto standard for generically describing algorithms, an ALGOL like language-very pretty!
Many of us have looked forward to Knuth rewriting his artful collection to satisfy our sense of aesthetics. We don't consider that he would have to repeat this huge task over and over again. Or (save me from this one) he could produce an obnoxious series of books titled "The Art of Computer Programming in C", "The Art of Computer Programming in C++", "The Art of Computer Programming in JAVA", "The Art of Computer Programming in C#", and (my favorite) "The Art of Computer Programming for Dummies". I thank Knuth for not doing this, although the last would certainly have a wide audience. Publishers know what they are about.
Another reason, in my humble opinion, that Knuth probably holds to MIX is that the latest generation of programmers do not have a clue what it is like to program a machine directly, or what is happening underneath the hood. There is a huge leap from MIX to MACRO, but the basic principles are still relevant.
The bottom line: YOU CAN COMPLETELY IGNORE MIX! All the relevant ideas are explained in simple plane English and the algorithms in structured English. Those who would prefer not to understand, but to simply cut and paste code, you are simply out of luck.
Now, if that isn't insulting enough (you caught me on a good day (after 32 years of programming I have come to hate computers and ...)) you would be amazed at how many self proclaimed senior programmers (programmers with more than three years of experience?) can't write an algorithm to save their lives.
BUY THE BOOKS! THEYRE A BARGAIN!
By the way, you all should read some of Knuth's other works. How many of us know that Knuth was an important player in getting rid of GOTO statements? I haven't written a GOTO statement in over twenty years! If my memory serves me (on a good day) Knuth wrote in an April edition of the ACM a paper titled, "Goto Bad, ComeFrom Good". He would be pleased to know that he anticipated the Publish-Subscribe Architectural Pattern.