One might argue that literature doesn't have to be interesting to read in order to be great.

I agree with Art -- I don't think we need a great American author to write about politics. In today's world, political ideas are not spread by novel, they are spread by newspaper and commentary and internet. We no longer need an author to write a whole novel on politics, publish it, and then disseminate to to the masses. By the time that happens, it's often irrelevant. Only a very few politic writing have maintained their relevancy through the years. "A Modest Proposal" is as funny and scathing as it was when written, but no longer has the power of relevance.

On the other hand, we have a whole crop of fiction writers who's every work is imbued with politics, even if they aren't writing about it. Heinlein, Tepper, Atwood...

On the non-fiction side, we have writers like Michael Moore, and countless columnists.

There's no lack of political writing, and no way to tell which novels being written today will be as powerful and relevant 50 years later as 1984 is today.