Im not sure I agree with the unworthy take on King Viserys. Nor the idea he made many mistakes. Perhaps sat on the fence at times he ought to have acted, but he never did anything rash, or terrible, or stupid. My take was more that Viserys was a good man, and thus the throne rejected him for that sin alone.
This is a common theme among GoT, what does it take to be a good king. Obviously you don't want to be a Tyrant, but you do need people to follow and obey you, and sometimes that requires a little bit of fear.
Viserys seems like a good man for the most part, but a good king? He's not a bad king, but you could argue his weakness has weakened his house and position over time.