Seriously. This should be the default setting on all devices. Accessing random open networks is generally not a good plan for many reasons...

Edit: (See below comments) I actually have the equivalent of what you are talking about disabled on my phone (android), as it creates a popup context menu that is too easily pressed 'accessing random open networks'. You want the user to have to open the wifi settings and select a network they know / have preconfigured, not some open network that the phone is eager to join.