It's interesting that the question of how hotels charge for wireless has gone through a few iterations. A few years back the higher end hotels were charging for it while low-end and mid-range hotels provided it for free. This seemingly backwards situation was understandable as a matter of price sensitivity.... Guests staying at pricey properties didn't mind an extra $9-13 daily charge for network. Many were business travelers who simply billed their employers or clients for the expense. This fueled a lot of ridicule from price sensitive travelers, including many cost conscious business travelers.
Today the high end hotels are still charging for wifi access and many of the mid-range hotels have joined them. The mid-range properties have copied the high end properties though they've done it under the banner of promoting their frequent guest programs. Book through the website and provide a loyalty program number, and wifi is free; but book through an opaque OTA like Priceline for a cut rate and you'll pay for wifi.
At the same time hotels have largely been able to get away with more frequently charging for wifi because fewer customers than ever before even care. Most travelers have smartphones and know how to tether. 4G bandwidth is good enough in most locations for this to be workable. Indeed, 4G tethering is faster than many hotels' wheezy, oversubscribed wifi services. The only place I really care about free, working hotel wifi is when I'm traveling overseas.