4. He has not won the Nobel Prize
In spite of his groundbreaking ideas and paperwork, Stephen Hawking has not yet won the ultimate award in science: Nobel Prize. This fact has its own pros and cons.
A Nobel Prize in science is awarded to people with groundbreaking contribution to the world. For example, last year, The Nobel Prize in Physics was awarded to the discovery of neutrino oscillations, which shows that neutrinos have mass.
The recipients, Takaaki Kajita and Arthur B. McDonald, did not just come up with the theory, but they discovered it.
In the other hand, Hawking has not yet proven his theory or contributed it in any tangible discoveries. This is why he has not yet awarded the highest acknowledgement in science community.