I think it's kinda silly; when I would go to the cafe, there were people working, and people talking. It's rather nanny-ish to decide what is good for others.
Two, it won't stop socializing people from checking their smart phones, which don't need wifi. Addicted people will still be addicted to checking every ping.
Three, a lot of people who opt to work at a cafe where they need wifi do so because they have nowhere else to go. I was a regular at Starbucks when I had no wifi at home. Maybe others have noisy homes, noisy neighbors or kids running around and the cafe is quiet by comparison. Honestly the cafe was noisy to me from the loud music and people talking, either on their phones or to each other, and I found it difficult to concentrate. But I needed the wifi.
Basically, I just see this as them losing business. It's pretentious of them.
PS, I like your bean art. :)