Well, intergalactic stars would be places you could actually visit and see, and many would even have planets around them. So there's a compelling case for showing them. Dark matter on the other hand is just just an invisible fog of particles around galaxies. If dark matter is added then I think it should be along with other non-visible things like magnetic field.
One question with showing intergalactic stars may be in how/where to generate them. The more simple population would be the hypervelocity stars, which were members of binary systems that got ejected by passing too close to the central black hole. So they should have some spherical distribution about the galaxy, almost like a very diffuse globular cluster. They would have fast velocities almost directly radially outward, but their motions would be unnoticeable except on very long timescales -- the same kind of timescale for which galactic rotation would be apparent. Such stellar motions likely will not be shown any time soon.
The other population are from tidal streams thrown off during galactic mergers, so they have more complex distributions which would require a new generation system. If SE simulated galactic mergers then they would be a natural occurrence, but that's also something not likely to be shown any time soon.