It's easy to not learn the first thing about the address bus, the address latch, etc. if you have a state-of-the-art processor that has everything on-chip.
which almost beg the question "do you need to". I guess that when someone get to where 128k of flash and 8k of RAM is not enough, the basic knowledge will be established in most of the other stuff. So the question really is "what should you learn first?".

this point, a person could buy a SiLabs kit and use a 'C' compiler and write some code knowing precious little about how it works.
In theory, yes. However if you read the SILabs forum you will see that it is not so. Many with questions at the SILabs forum have been helped by "the bible". One fact about the SILabs chips ia that for some derivatives, in some applications, there is no way around modifying startup.a51 in assembler

I'm hoping my book produces more knowledgeable developers rather than just code monkeys that can write code but have no idea how it works or whether or not it is efficient.
I definitely share that hope.

I fear that basing everything on state-of-the-art processors might hide too much of the inner workings that separates a code money from a knowledgeable 8052 developer.
Well, that is my argument for using a chip with ICE functionality.

Remember that I'm talking about a book that tries to teach these concepts. I'm not arguing what is better for the professional or experienced developer. I'm wondering which approach is most instructive for learning.
I kind of wonder myself, so - who knows. What I state re "under the hood" etc is, of course based on what helps me the most.

And while ICE is great, I think you ultimately learn more by banging your head trying to figure out what's going wrong by having to think about your code and trying to consider where it could be failing rather than just stepping through it until your program happens to do something you weren't expecting.
Here I (partially) agree. It is a fact that no one approach, regardless of which you choose, will lead to succesful, efficient debugging.

You could quote Dolly Parton on page one of your book
"Y'all have fun now, ya hear"

Erik