I have been racing MX basically my entire life , and in our life time , I don't think we'll ever see a " real motorcycle sim ".
In our car sims.....we worry about the car behavior , and it doesn't matter what our body does in the car , except to just steer the car. On two wheels......98% of what you do on the track is controlled by your body. You don't just turn the bars and give it gas. I can say with 100% certainty , that MX is the most brutal sport I have ever been involved with.....and that's without going down and breaking something on your body. I've raced going on 35 years now , and have literally broken almost every bone in me , at least once , some more than twice. To actually " simulate " how to ride / race a bike properly? That's above my pay grade , but it would take something not yet invented for gaming yet , and that would be way for it to read what your body is doing , along with using bike controls.
It's one thing that I don't think will ever happen in our life time , because to achieve it....would cost a lot of money. It would be a lot cheaper to just buy a " real " bike and experience it yourself. It's the best feeling in the world , I can tell you that much.