Wifi hotspot asks for personal or corporate/server ID of the sender of packets coming from this new node, since it can't route the traffic any farther without that. Gets nothing. Drops that node's packets as either hostile or malfunctioning, and, regardless, useless, since it can't route them anywhere. OK, so maybe you manage to steal an ID. See how this is making attacks harder? Now you're stealing or forging identities just to get any packets routed, and if you do anything suspicious-looking you'll rapidly get your stolen ID on the automatically-managed collective shit-list and it'll stop being very useful. Because the volume of attacks is so much lower, your drop-a-radio-near-a-hotspot trick might even trip enough flags to get someone to come find the device, if you use it very much—and if you can't use it much without "burning" the hardware, then, well, sure seems like it made your job as an attacker a lot harder, right?

There is nothing that guarantees the Internet will keep working the way it does now, and if an open Internet causes enough problems, it will be reigned in. How it works now is a choice, not a law of nature. I'm not happy about it, but that's just how it is. Either these kinds of attacks won't get much worse, or they'll get a lot worse and something like that will be what happens.