I had a good chat once with a guy who runs a small coffee roastery and number of fancy third-wave coffee shops in a posh university town. One of the most popular coffee shops in town went completely bankrupt and he ended up taking it over. The first thing he did was turn off the WiFi; to hear him tell it, revenue doubled or tripled overnight as soon as he did. Turns out actually having available seats can drive sales, and having a giant store in a high-rent area full of people who buy one $4 coffee and sit there for five hours isn't profitable. At the time, he was in the process of renovating half of the space to be formal paid coworking.
(I personally think there's room for middle ground. My favorite local coffee shop only allows laptops in a dedicated section, which has ample power but also higher-density seating than the normal area. When it's warm enough to sit outside, they allow laptops outside during the week but not on weekends. Another favorite coffee shop just turns the WiFi off on weekends.)