It's just a value-add thing. I work for one of the smaller MSOs that hasn't yet deployed wifi large scale but all the vendor material I get on focuses heavily on the value-add angle. I'm not super convinced it works but let's say you're considering a switch to telco video or satellite you might think twice about it because you use Cablevision wifi at the coffee shop. Telcos pioneered most of the bundled wireless deployments so there's some pressure for cable to offer it just to say they have it. It's cheap to deploy and maintain too so why not? For the bigger MSOs it's a tiny expense.