I wouldn't assume they don't care. The majority of people still using IE6 do so because it's the only browser their IT department will allow on their workstations (http://about.digg.com/blog/much-ado-about-ie6).

That said, because of the difficulties, it's generally acceptable to provide some base functionality/design for all browsers while layering on cool CSS effects for modern browsers as a form of progressive enhancement (using CSS border radius for example).

Of course, all of this depends on your specific user base and the importance of those IE users.