Well duh! Of course the political conventions are manufactured drama. People act like that's a big revelation. In a way, politics is theatre. Speechwriters, like songwriters and playwrights, make an appeal to people's emotions. The words they use, the images they construct, are all designed to conjure a specific picture in the minds of the audience.
Sure, it would be nice if people made their choices after spending hours watching C-SPAN and poring over position papers, but they don't. At least I don't. I mean, I know something about where a candidate stands on the issues, certainly. I read newspapers and magazines and catch snippets of speeches on television.
I realize that there are more concrete aspects, too, like which candidate has a better plan for the economy or bringing the troops home from Iraq. Still, you can't really know how that candidate will act in every situation. But you can have a sense of which person shares your values, which candidate will do a better job protecting the things that are important to you.
And really, is it so different in the theatre? Isn't that part of what hits us with a play or musical that we love, because something about a performance or a subject resonates?