I found a great article from last year in Ars Technica about working in cafes. The last paragraph summarizes things nicely:

Personal experience suggests that most laptop users who work at coffee shops don’t do so because they are too cheap to rent an office. No, people whose work involves the solitary punching of laptop keys enjoy being around other people, and coffee shops and cafes provide a comfortable and inexpensive environment where one can feel less isolated while working. Looked at in this way, the “WiFi wars” are less over Internet access and more about the type of jobs that we do—jobs that require little human interaction but do require the constant tether of a network connection.

Ars Technica article