When you are a famous person or artist or "placeholder-for-any-person-capable-of-influencing-lives" you must realize that you made a contract with Society: You will have certain privileges and you may (or not) be upheld to certain view or standards... Your privileges do come with exigences... Whether you admit it or not.
A contract with society? I dunno about that. He got lucky (along with his skill) playing music and is among the wealthiest musicians around. Privileges...okay, wealth, but still, what makes these peoples view special, other than they are well known and wealthy.
Sure, hold people accountable for their views, but why expect more out of Roger Waters than you would expect from some pub musician. He isn't a scholar or philosopher, he is a musician. He is better than the pub musician, but at being a musician, and perhaps nothing else.
Because their professions usually entails travel and exposure to different cultures, beyond that of the average person who has never had that opportunity.
I don't agree - taking drugs and drink with people from different nations around the world isn't what I would call exposure to different cultures. I don't think doing this kind of thing opens people up more to the cultures of other people, not more so than staying at home and borrowing some books from the library about different peoples of the world.