[jmull]

That same argument applies to numerous web technologies, though.

Applied to each individually it seems to make sense. However the aggregate effect is kill off a substantial portion of the web.

In fact, it's an argument to never add a new web technology: Should 100% of web users be made vulnerable to bugs in a new technology that 0% of the people are currently using?

Plus it's a false dichotomy. They could instead address XSLT security... e.g., as various people have suggested, by building in the XSLT polyfill they are suggesting all the XSLT pages start using as an alternative.

[cyanydeez]

depends entirely on which technologies are acctively addressing current and future vulnerabilities.

[dev0001]

The vulnerabilities associated with native client-side XSLT are not in the language itself (XSLT 1.0) but instead are caused by bugs in the browser implementations.

Ps. The XSLT language is actively maintained and is used in many applications and contexts outside of the browser.