It appears that docutils depends on pygments but doesn't express that dependency in setup.py. Unless there's a good reason to leave it out, it seems like a good idea to include it. As it is, some projects that use docutils need to explicitly list pygments as a dependency.
Thank you for the report. However, Docutils does not depend on Pygments -- it works without errors and according to the specs without Pygments.
Code syntax higlight is an extra provided by Pygments. This would merit a "suggests" or "recommends" entry but not a dependency.
The "good reason" to leave it out is, that it is a core feature of Docutils to work without any external dependencies (besides stock Python, of course). Projects using Docutils may decide whether syntax highlight is essential to them and eventually state a separate Pygments depencendy based this decision.