In my opinion, there is no reason for celebrities to refrain from making comments on politics. Celebrities are citizens and residents of the country, just like anybody else; and they have the same right to free speech. When celebrities get involved in politics, this increases the general public's interest in politics as well, which is a good thing.
Yes, celebrities should be able to comment freely on what is happening in the political sphere. Everyone can and should benefit from the free-speech rights afforded in the constitution, whether they are a celebrity or not. No citizen should feel fearful or embarrassed to express themselves and share their views.
Yes, celebrities should make comments on politics. Celebrities are not only individual citizens with rights to voice their opinions, but they are very influential in our society. People look to them for direction in how they should dress, what is popular, what music to listen to, etc. Politics would be a great area to influence public on.
While most of the celebrity commentary on political matters is facile, there are a few individuals who are capable of making valid contributions. Celebrities such as George Clooney and Angelina Jolie have shown that they are competent operators on various political matters and they have gained expertise which shouldn't be dismissed because they have worked as actors.