Comment 21 for bug 510010

HTML4 says that the media attribute applies only to style sheets:
# This attribute specifies the intended destination medium for style information.
# It may be a single media descriptor or a comma-separated list. The default
# value for this attribute is "screen".
  --http://www.w3.org/TR/html4/present/styles.html#adef-media

Current HTML5 draft says:
# The media attribute says which media the resource applies to. The value
# must be a valid media query. [MQ]
#
# If the link is a hyperlink then the media attribute is purely advisory, and
# describes for which media the document in question was designed.
#
# However, if the link is an external resource link, then the media attribute is
# prescriptive. The user agent must apply the external resource to views while
# their state match the listed media and the other relevant conditions apply,
# and must not apply them otherwise.
  --http://www.w3.org/TR/html5/semantics.html#attr-link-media

So this feature request isn't even backed by any specifications.