The reason things are labeled is so you know what you're buying. Brands have a reason for existence. Who want's to pay Rolex prices and get a Timex? Taking on and accepting a label, whether Republican or Democrat means that you intend to approach politics from a particular set of views. You may not perfectly reflect them, and you may not accept them all, but to take the label, you must fit into the outlines of the Brand.
...I'm trying to figure out just what it is about No Labels that irks me so.
In part, it's the self-congratulatory, schoolmarmish earnestness surrounding the campaign. No Labels actually gives out a label: the "Problem Solvers Seal" for candidates who have committed "to join a group of Problem Solvers." It's as cloying as a "Mean People Suck" bumper sticker and promises to be just as effective.
With no-labels politicians, you don't know what they stand for, except to get re-elected.