The short answer to the first question is yes. It's a Constitutional right--for those who live in the United States, that is.
The long answer, on the other hand, leads to the second question.
The answer to that one . . . I'm not so sure on. We should be able to share our opinions, but at what cost? If you publicly criticize the way your government is being run, you may be praised or you may be outcast--this depends largely on what political party is in power.
Does this mean I don't believe artists should be able to share their opinions on social views or poltics? For me, it depends largely on what it accomplishes. Also, some people are really good about expressing their opinions, and it is even a part of their platform (i.e. Sean Hannity or Ed Schultz).
Is it safer to take the neutral ground on such hot topics?
Take the issue on gay marriage. There are strong supporters of it as well as strong opponents. But if one takes a side, are you alienating the other? If you are a strong opponent, are you seen as simply homophobic?
Something to think about. I'm not sharing my opinions, and for the most part I keep an open mind about such things--I have this uncanny ability to view things from various points of view. There are a number of artists who are also in this camp.
So at least I'll have company.