> After having revised the XHTML 2 WD another time, I again 
> wondered about the use of the <th /> element -- wouldn't it 
> be simply enough to use the <thead /> element instead 
> surrounding the corresponding table cells, 

One use of a table is a spreadsheet; the table may be 
modified (including reordered) based on user input.
The headers typically are not subject to the same filters.

You can override the <td> styling with <thead><td> if
you know exactly what you want.  It is awkward to say
"I'm not sure exactly what <thead><td> *should* look 
like, but please ignore the <td> rules.  Well, some of them."

-jJ