I would like to ask you whether it could be a good improvement to assign a
  notice, whenever "make install" actually installs a binary software.

We have talked about this occasionally.  I believe that we should not
add this feature to the licensing framework.  It might well make sense
to add a way to denote various attributes of packages so that people can
be aware of attributes that they don't like.  The difficulty is defining
a set of attributes that would be useful.

You have suggested "binary", but that's actually more subtle.  There can be

  binaries for which no source is available
  binaries for which source is available, e.g. openoffice from oo.org
  binaries built as part of pkgsrc ("make bin-install")

Then, there's the issue of whether the feature is useful enough to
justify the maintenance headache.  Do you think there are a lot of
people who are willing to add many non-free licenses to
ACCEPTABLE_LICENSES but who are unware that software with icky licenses
often comes as binary only?