On Punditry

I'm not sure if I feel like crap because I've been playing video games all night or if I've been playing video games all night because I feel like crap. And not speaking of celebrity pundits, I've been thinking tonight about celebrity pundits.
Someone I know of once walked out of an REM concert, complaining he'd paid to go to a concert, not the democratic national convention. That's a pretty fair point. I've never been to a rock show that I can remember at which my political opinions varied so much from the political opinions expressed by the artists; I lean in the same direction as most of the music industry - the entertainment industry. I'd be pretty annoyed if all my idols used their fame to tear at my ideology. 
And that got me to wondering. What qualifies celebrities to try and impose their opinions on their fans - on anyone who will listen? Celebrities like Pam Anderson, whose only discernible talent lives inside her bra, spends half her life stumping on behalf of PETA. PETA dumps tons of cash into opposing medical testing on animals. Ipso facto, Pam Anderson's boobs, whether you agree with them or not, are affecting policy and legislation on legislation could save your life or my life one day. Should, perhaps, questions of biomedical ethics be left up to people whose assets are inside their heads, people qualified to understand and logically consider all of the factors involved? 
Or Jenny McCarthy, whose accomplishments include Playmate of the Year and posing naked on a toilet in a national ad campaign. Ever since her son was diagnosed with autism, she has been traveling around the world shrieking about how vaccines are to blame. Despite their being absolutely positively no credible scientific evidence that this is the case. Because people who pose naked on toilets are more qualified to make these determinations than, say, Nobel prize winning scientists. The thing is that without vaccines, people die. Kids who don't get vaccines die. Kids who are too young to get vaccines die from diseases they catch from kids who didn't get vaccinated because a playmate told their parents to ignore science. Are there factors that parents have the right to weigh before they vaccinate? Sure. Should one of those factors be a celebrity pundit? No. 
Now this is kind of tricky, because my Bruce is one of the loudest celebrity pundits of them all. But great artists throughout history have used their art, and the celebrity that came with it, to push their agendas. Is Jon Stewart's satire all that different from Jonathan Swift's? Was Mark Twain unqualified to argue against slavery? 

I'm not sure. I'll let you know when I figure it out.