The biggest thing with the older ones is the lack of assumption of Internet, so the book will refer to itself instead of referring to online/other documentation.
I've learned things reading a "Missing Manual" for an operating system that is 15 years out of date that still work today.
I also miss this aspect of old books. They were more self-contained.
But I feel much of the documentation/reference around things from 2010 is both late enough that it wasn't printed, and old enough that what was online has failed or faded away.
Nowadays if you need to change a setting, you not only have to contend with major version but what biannual revision of windows you are using, and hope that someone at Microsoft hasn't decided to move that option in an update.
Compare to far too much online documentation. This is what I've frequently run into. I want to learn about some particular subject, so I find a site that has an introduction or tutorial on that. The document is even book-like in the sense that it is organized as pages, and at the bottom of each page there are "next" and "previous" links.
But there is a sidebar on each page, with lists of related material and some of that sounds like material I'm going to need to know at some point. But there is no indication if it is material that I'm going to come across later if I just keep following the "next" links or it is something beyond the scope of the current document that I'll need to bookmark now to come back to later.
And if you put it down and pick it back up tomorrow, it will still be where you left off.