From my point of view as realism-nut two things:
- A random at least, and dynamic if possible campaign is something that any enthusiast will rquest
Adds the element of uncertainty (As in real life) and loads of replay value.
- Ability to operate yourself as many systems as possible, or let the AI do it.
Of course a great physics model with believable dynamics is always welcomed, but that one doesnt need to be ultimately perfect, just a good one should suffice.
A good example of the style of game/campaign I'm thinking of, is "Red Storm Rising"
