Hi Dan,
The "banishment" of the target attribute in XHTML strict is the topic of many discussions on the Web. Just type xhtml strict target _blank in Google and see for yourself the pros and cons. See for instance: How evil is the target attribute?
Personally, when I am surfing the Web, I do want external links to open in new windows (or, preferably, in new tabs). I hate it when an external link opens in the window I am actually browsing. Just to make sure the latter does not happen, I usually right-click on links and specifically ask for "new tab" location.
I do appreciate that this is very subjective and that other people may hold exactly the opposite view.
What I find irritating, however, is that the people in charge of XHTML strict have taken the decision of "deprecating" the target attribute, thus favoring one point of view, rather than letting web pages designers free of their choice.
Joseph