2 of my favorite coffee shops (Filter and Peregrine in DC) are really small and constantly full of people working on laptops. I love the coffee but don't take guests or coworkers there because there are never open tables to sit and chat. I know other people who avoid them entirely because having sitting space is more important to them than the coffee itself.
People who stay for more than, say, an hour or two hurt turnover which is critical for smaller coffee shops that also serve food or snacks, whereas places like SBux make most of their money on people getting a quick morning fix, and can also afford bigger spaces.
I'd prefer if things bifurcated, big national chains that can afford the room offer wifi, smaller local places kill it to keep turnover up. I can see how it's a lose-lose for coffee shops having to choose one group or another. Some places turn it off after, say, 3pm which is a nice compromise.