This is BS in 2012. Hotels need to treat internet access like running water and make it at least as good as what people get at home. Especially when you consider many people in hotels are subject to international roaming fees if they resort to their mobiles.
Even in higher-end hotels, you get a shoddy experience, and not just this ad injection.Weird login dialogs every few hours and restricting access to one device. Outrageous fees. Lack of transparency on bookings websites about availability and pricing. And once you're online, good luck trying to watch a video or getting any work done, the connection's often too slow to do anything but check a few emails.
I really hope AirBNB puts pressure on the hotels to get their act together. You stay in someone's house for $40 and you get a much better experience than a $200 hotel room. The whole situation is why I recently made the decision to use AirBNB instead of hotels whenever practical.