I have a habit of looking at the calendars of the tracks F1 goes to, just out of curiosity. Many of them have bicycle events in addition to car events, for exactly the reasons you would think (and mentioned): well-maintained roads with no cars, an interesting, undulating course, nice surroundings, and infrastructure for crowds.

As an example, the 2020 UCI Road World championship was centered around the Imola track, and looking at their schedule they frequently have other cycling events.