There was a big transition over the past 10 years when coffee shops went from being smoking establishments mainly catering to young people and people on the fringes to being places where a wide demographic of people meet to talk and, for many people, work on computers. Laptops + wireless breathed new life into independent coffee shops at a time when they were being hit with smoking bans and still licking their wounds from a decade of starbucks expansion.
The transition to wireless has created a thriving cafe culture that's more busy than I've ever seen it. The cafes around me are so packed all day every day that I have to time my arrival to make sure I get a seat. 10 years ago they were mostly empty during the day. And it's not just more customers, it's better customers. Schizophrenics who sat with a single cup of coffee for hours while harassing other customers have been replaced by young professionals who buy double lattes.
The vast majority of coffee shops that didn't embrace or take seriously the transition to wireless have lost all of their customers and closed. It's been somewhat heartbreaking for me to watch some of my favorite coffee shops sit empty and eventually close down because the owners didn't take the wireless transition seriously and/or because they held on to an imaginary ideal about cafe culture.
Turning it off on weekends makes some sense; people aren't working there as much. However, it's a dangerous idea for cafe owners to take the anti-wireless sentiment too far. It reminds me of when I worked in academic libraries during the period they were still holding on to their luddite fantasies about the role of libraries. If you own a cafe and are considering this, you better make damn sure that your cafe has enough of these ideal, laptopless customers. I've seen a lot of cafes gamble on this and lose.
All that said, it's interesting that wireless has made coffee shops so popular that people once again value them as social centers.