In the immortal words of Dirty Harry Callahan, "A man's got to know his limitations." These days all too many folks don't seem to think they have limitations, probably due to overindulgent parental units as well as all those "Do It Yourself" TV shows and magazine articles that try to convince ordinary clueless individuals that anyone can do brain surgery as long as they buy the right tools.
Sadly, anyone can walk into a motorcycle dealership and buy anything up to and including a thinly disguised racing bike that will do close to 200 mph. The dealership might notice the buyer's severe lack of coordination and obvious lack of experience, but if he's got the money or the credit they will sell him whatever he wants and not worry about making sure he can actually ride it away from the dealership. I've seen guys crash before they got off the dealer's lot, and even saw one instance where it was immortalized in print in the local newspaper, with the guy not only crashing but also doing several thousand dollars worth of damage to a dealership employee's car.
Anyhow, back to the subject. NO, obviously not everyone is physically or mentally equipped to ride a motorcycle, just like not everyone can fly an airplane. I personally believe a separate motorcycle driving license should be an absolute minimum requirement, and it should include actual riding tests and not just a true or false written exam.
Jerry