I started deleting all exceptions a few years ago anyway. I use Google only when absolutely necessary, but have used Wikipedia, as both guest and registered user, including secure version, many times, with no XSS errors at either site. Couldn't create one in Yahoo search, either.
Last mention of XSS re: Wikipedia is
or more than five years ago.v 1.1.4.8.070424
x Improved Wikipedia XSS exception
Wikimedia:
(doesn't specify XSS)v 1.1.9.9
x Better compatibility with Wikimedia sites
With the continued fine-tuning of the XSS sensitivity, perhaps these may be deleted as defaults -- unless anyone can show a reasonable set of steps to trigger an XSS message when these exceptions are removed?