Ofcourse, but open wireless nets is becoming a thing of the past these days, just sitting here at home I see 8 networks, of which none are open, 2 are WEP, 5 are WPA/WPA2-PSK and 1 is WPA/WPA2-EAP/1X. Our "city net" is also uses EAP/1X, at least that is how I connect to it (eduroam).
It's not just about encrypting the wireless line, it is also about making sure the client connecting is allowed to do so, hijacking authenticated sessions on web based portals is just too easy.