Why isn't DeLay Pretty and Articulate?

So I just saw the video of Tom DeLay saying nasty things about Mr. Schiavo. (Yes, I'm a little behind schedule this week.) Anyway, it's not a surprise the whole Schiavo thing is turning out to be a disaster for the GOP when you've got DeLay and the Christianists out front on the issue. The guy's apparently the most powerful guy in Washington who's not in the White House, but he comes across as a total prick on television. Makes you wonder how the guy can be a politician who has to get elected. But this isn't unusual: both Kerry and Bush are awful speakers and not particular good at being on camera either. Why is this? You would think, in this day and age, that every politician would look like a model and speak like a news anchor. But they don't. In fact, they seem to be getting worse - Clinton being the only exception I can think of since Reagan. I can think of a bunch of silly theories to explain this phenomenon (anyone actually good-looking, articulate and rich can make their living otherwise, politicians are supposed to appear like the "genuine everyman," etc.) but they all suck and can't possibly explain this.