Well, this is going to be a
stupid writeup, but what the heck....
Apparently, none of you have ever witnessed or seen the aftermath of a car-motorcycle collision. Believe me - you are fooling yourself if you think a 500 lb (or more!) motorcycle presents no threat to an auto, even an SUV. Rest assured that a 70 MPH bike is a very dangerous projectile, capable of splitting a car nearly in two, particularly in a broadside collision.
Besides - why bother raising the speed limit for motorcycles? From what I can see, most motorcyclists who wish to speed already do so with wild abandon.