I'm reading this book and I don't understand why version 1.0 would be the baseline if there is a version 1.1 out. I understand why 2.0 isn't becuase it's in the working draft form. Now this book is like 4 years old so please tell me if this has changed or this is wrong but please me why they would use an older version. The passage from the book is below...

HTML and XHTML specifications
The formal documents to describe HTML and XHTML are on the W3C’s Web site at www.w3.org.
Markup languages usually include version numbers to identify them. The current version of HTML
is 4.01. It dates back to December 1997; you can find the document at www.w3.org/TR/html4.
XHTML has gone through two major drafts, 1.0 and 1.1. The 1.1 version is more advanced than 1.0,
but most Web content developers and software tools follow the 1.0 specification. An XHTML 2.0
specification is in “Working Draft” status (its authors haven’t finalized its content and structure).
When a W3C specification is finished, it’s known as a W3C Recommendation.
You can find specifications for all three versions of XHTML:
 XHTML 2.0 Working Draft (7/4/2004)
www.w3.org/TR/2004/WD-xhtml2-20040722/
 XHTML 1.1 Module-based XHTML Recommendation (5/31/2001)
www.w3.org/TR/xhtml11/
 XHTML 1.0 Recommendation (1/26/2000)
www.w3.org/TR/xhtml1/
Reading W3C specifications takes some learning and improves with repeated exposure. Don’t let
the formal language and notation of these documents put you off: After you understand what’s up,
you appreciate the precision and detail! But you may decide never even to look at one of these
specifications — it’s entirely up to you!
The HTML 4.01 specification is the rulebook of HTML, as the XHTML 1.0 specification is for XHTML —
each one tells you exactly which elements you can use, which attributes go with those elements, and
how you use elements in combinations to create such page structures

Bump... (because I want this answered)

All of my html is 1.1. I just wrote my code and it turned out to be 1.1. I think 1.1 is the way to go.

Maybe because web designers do not like change. They all say "Stop leave me be stop changing my code" lol.

Damn right! We have enough crap to worry about without worrying about someone changing our code!

Neither XHTML 1.0 nor 1.1 are really better than HTML 4.01 at the moment since Internet Explorer does not support XHTML. That said, the most useful feature that XHTML 1.1 has over XHTML 1.0 is XHTML Ruby.

Unfortunately, the only browser that supports XHTML Ruby (Internet Explorer) is also the only browser that lacks support for XHTML. (Internet Explorer implements Ruby elements as proprietary HTML elements. I’m guessing that they implemented it since one of their employees wrote the CSS3 Ruby spec.) It looks like Mozilla is doing some work on Ruby again, but I don’t see it being implemented any time soon. I can’t really blame anyone for not implementing it though; the basis for XHTML Ruby is CSS3 Ruby which, IMHO, is very poorly written.

So, the point is that the most useful feature of XHTML 1.1 is currently useless and, thus, XHTML 1.1 has no notable advantages over XHTML 1.0. Also: XHTML 1.1 has also reverted back to W3C Working Draft status (from W3C Recommendation status, no less) so it’s no longer part of a final specification; the HTML 5 Working Group has declared that HTML 5 is the successor to XHTML 1.0 (i.e., XHTML 1.0 advances to “XHTML 5”, not XHTML 1.1 or 2.0); real XHTML can’t be used on the Web, generally, thanks to Microsoft; and the “HTML‐compatible” features of HTMLized XHTML are removed in XHTML 1.0 (i.e., Appendix C). Thus, you have few reasons to use 1.1.