You mean, to highlight text/plain (or any text/) files (depending on
extensions), and messages (e.g. display messages as stx, or recognize
*bold*, /italic/, _underlined_ on a per-message-configurable basis)?

Yes, indeed.  You don't happen to have written an extension already? ;-)

I think we shouldn't introduce a new dependency, thus we should have a
fallback strategy for pygments not available, like we have with pytz.