Charging for hotel wifi is about price discrimination. The only people willing to pay $25/day for in-room wifi are business travelers who aren't paying for it themselves anyways.

That's why you're more likely to pay for wifi at a business hotel (Marriott/Hilton) than you are at a tourist hotel. It's also why you're more likely to pay for it at a more expensive hotel than a less expensive hotel.

Frequent business travelers care a lot more about reward stays than they do about free wifi (because they're not paying for it, and because the loyalty program will give it to them for free).

The article reads more like a press release for a social media agency (which is who they quote in most of the article) than it does an actual analysis of why hotels charge for Wifi.