Additional throttle management mechanics for more authenticity.
Full throttle while clutching out of a turn should invoke a power slide with counter steer as a risk/reward feature. Too much throttle leads to a high-side crash or swapping stun animation and not enough just means you're not optimising the corner. While applying the perfect amount gives you the best turning radius for the speed (think slightly tighter turning at 'X' speed).
At the moment when you apply full throttle on a berm the bike wants to maintain max traction and just veer off course in a wide arc unless slowing.
Allowing that rear tyre to break traction and induce power slide with counter steer would be juicy.
Different parameters for soils types which could add more dynamics to wet races and sand.
You could even go into braking with an understeer mechanic/animation. At least that way, the people complaining about it feeling slippery will get visual feedback when they're going too fast.