I think in general in sims the only real reason why we don't have reverse layouts in sims is because the devs just don't want to make them. The reasons could be purely ideological (real life) or it could just be that the extra work that is needed is not considered worth it. I can understand the 2nd argument but the first one seems a bit pretentious. But even then a personal feeling about what is good or bad may not be shared by most other people. Lots of people like tracks I don't and vice versa so it is somewhat difficult to be someone who has authority over taste about race track quality.
While there are lots of reasons why a track can not be driven in opposite direction in real life there really aren't that many in sims. Even serrated kerbs (
image example) can be easily driven in the wrong way in sims. The ffb might be more harsh but the sim cars can take it just fine. As long as low cars won't get launched airborne I don't think there are any real issues there. Safety areas don't matter at all in sims. Sand traps might be in wrong places so if you go off chances are you hit a concrete wall at really high speed. If there is a wall there at all. But then again in sims all walls are essentially concrete walls as only a handful of games ever have tried to simulate any kind of deformable barriers or tire walls.
Kerb placement could be annoying. If a corner has really small apex kerb it might not be in the apex anymore when you drive in opposite direction. Some corners which need exit kerbs may have none. Pit entry and exit could be in awful places on opposite tracks. Just imagine getting t-boned in spa when exiting pits when a car missed braking point. But that is really small annoyance in the end and some real tracks have really horrible pit exits like lime rock so it is not a realism killer either.
I think for sims the things you need to do in general is a list like this:
- pit slots and starting grid
- timing gates
- ai lines (racing line and pit line) and all other ai adjustments
- adding braking markers and start lights (the few things that really require 3d modelling but not necessary)
- might need new track cameras, probably not
- any additional features like time trial gates
- and testing
For many tracks in a modding platform like in ac this can be done as a mod that works as small drag and drop package. In most cases you just need one small kn5 file and new folder for the track layout ini files.
For relatively low effort you can get a new track into the sim. I'd really wish more sims would do it.