I watched Gigantic recently, a documentary about They Might Be Giants. One of my favorite parts was a short clip of an interview with a guy who just couldn't understand why they had written Meet James Ensor. He said he had questioned the Johns repeatedly about why they would bother writing such an odd song about an obscure Belgian painter, but the only response he could get out of them was "No, really! He's a great painter!" I found that highly amusing, especially since I thought the guy was getting way too worked up about it. For some reason, he just couldn't understand how that would be a legitimate song topic.
One of the things I really like about TMBG (and I think a lot of their fans agree) is the variety of things they write songs about. Belgian artists, ants, tiny doctors, stopped clocks, blue canary night-lights, whatever. I think it's delightful. Makes me wonder, though, what that guy thinks songs "should" be about. If you can't write about whatever inspires or interests you, then what's the point?