I think the reason academics don't publish their code is that they don't want to get stuck into an endless discussion on the code along with people asking for "support" on it.

What I have found is that if you need the code for a specific data analysis then send an email to the authors of the paper. More than ever you will be surprised. They do share code with fellow researchers.

So - if you do really want code, write the email. Be forewarned though - the quality is often bad from a s/w engineering perspective and suits a very specific purpose. It will also come in a language of the authors choice (Tcl/Tk for ns2 scripts, matlab scripts, octave, etc.)