I'm currently a student getting a master's in computer science. In my experience, having the code available in research papers is rare, but useful. Many times I find myself struggling to understand how something can be implemented or, when presented with choices, choosing one when reading research papers. When the paper has the code published I am able to follow it better.

Some papers link to the code instead of including it. Maybe I'm just unlucky, but this usually leads to dead links (but that's a different topic altogether).