Have you ever actually looked at what they take out in fees? I changed money at Charles de Gaulle once and it was brutal, like getting half the local rate! My friend warned me but I was stuck without cash. Never making that mistake again.
My friend got hammered by fees at a currency exchange in Madrid last year. He was desperate for cash after his bank card got blocked overseas. The posted rate seemed fair, but hidden charges took a huge bite out of his money. He ended up with so little cash that he almost couldn't pay for his train ticket. It was a harsh lesson about always having a backup plan when traveling. Those airport kiosks really do squeeze every last cent from you.