IMO AMS 1 usually came across to me as having too much grip on the grass both in Reiza's tracks as well as mod tracks. AMS 2 OTOH comes across as excessively lacking in grip to me. If you could somehow split the difference between the two it would feel just about right in my book.
In a substantial majority of circumstances, I agree grass probably should be the equivalent of ice. It is not, however, completely impossible to save a slide on grass in the real world. In AMS 2 though, get on the grass at any speed with any degree of yaw and you *will* spin. At least that's how it comes across to me.
FWIW check the save at 4:36 in this video. I'm specifically referring to after the car comes out of the gravel. It's still in a slide but the driver maintains control over it and avoids wall contact. To me, AMS 2 feels as if a mild slide like this is impossible to save.
Now with all that said, this issue is *way* down my personal priority list of what I'd like to see Reiza look at. The simple reason being I have control over it by...you know...not going on the grass.