Any motorcycle, road or off road, has the ability to reach speeds that will kill you. 40mph or 140 mph, hit a tree and you are basically toast. Ideally, the licensing regulations need to match maturity and judgement with speed and horsepower. Anybody have an idea how to do this?

Good hunting

Next thing will happen is there will be a lot of straw man purchases of liter squid bikes, and a lot of outta state bikes.  

And Harley will come out with a sub 600cc cruiser.  

Hey!... who's lobbing for this anyway?  

It was that way in Australia for years: a learner or probationary rider was stuck on a 250cc bike for the first couple years, then could upgrade to a full size like. Now we have the Learner Approved Motorcycle Scheme (LAMS) where it's a power to wieght rule. So learners can ride bigger, more appropriate bikes. There's an upper power limit of something like 38hp, so we have  a situation where you can buy the same bike, new in restricted LAMS form, or the full fat unrestricted one. It seems to be working well.

Here in good ol' Utah, we have four classes for motorcycle licenses.
90cc or less
249cc or less
649cc or less
650cc or larger tested on, you can ride anything.

I was "grandfathered in" when that happened a few years ago. Wouldn't have mattered, I tested on an 803cc.

All that would really happen if you got pulled over and you were on a larger bike than you were licensed for is a verbal warning. Then a ticket for whatever you did to get pulled over in the first place.

Just another example of government stupidity and nanny state mentality.  If you can operate a motorcycle (any motorcycle) safely enough to be allowed on the road, that's all they should be interested in.  Being able to handle the size, power, speed, etc. is the responsibility of the rider. Process of attrition weeds them out much faster on bikes than in cars.  It's just another way to get more money out of the people. Just like the separate 3-wheeler license that I believe has covered most states by now. If you can operate one safely, you are capable of operating all similar vehicles safely.

I took my license test on a 70's chopper. Was told by the examiner that I was the only one in his 30 years of testing that had ever passed on a chopper.  Back then the motorcycle license meant you could drive anything powered with less than 4 wheels.

Licensing of any kind for operation of any vehicle was declared unconstitutional by SCOTUS back in the early 1900's.  But, since the judiciary has no power to enforce and the states saw a cash cow, here we are being extorted by our government for doing what it is our right to do.