Political Art?

Hi everyone, here is something I've been wondering about for awhile and I'd appreciate your thoughts on:

What, if anything, is the value of political art? Up until recently, I've thought that, in theory at least, the most well-done kinds of art are the ones in which a particular worldview, particularly a political stance is cleverly hidden "behind" the medium of the art. Now I'm starting to question that. I'm beginning to think that art, whether it be literature, music, painting, drama, what have you, concerns matters that run deeper than simply getting people over on your "side" in some particularly stylistic way; art, in its greatest form, seems to be exploratory rather than didactic, a vain attempt to express the inexpressible with the knowledge that it can never be done, but the results are quite beautiful anyway. Political art, on the other hand, exists to serve a purpose other than it's simply being; it's an especially useful rhetorical tool.

Take Macklemore's "Same Love" for instance:
http://www.youtube.com/watch?v=hlVBg7_08n0

The message in the song is important and I no doubt agree with it, but with the exception of Mary Lambert's vocals, the song to me has always felt forced, like it's a sung list of a set of reasons to support a particular view (again, I applaud the artists' efforts and intentions, but most of the song's lyrics would be more at home in an essay than in a song). Lambert's chorus however, strike me as different than Macklemore's verse and thus almost out of place in the mostly-political song; her repetition of "My love, my love, she keeps me warm," hint both at the sweet comfort and at the unfathomable mystery of love. Macklemore's lyrics are a political stance whereas hers are a personal expression that, for me at least, hit much closer to home as to what good art is.

Thoughts?