Bad ideas which at the time looked like ... bad ideas
Credas: " 'Many suspect that Loon will also join the list of projects that seemed like a good idea at the time but really weren't.'
"More like the equally long list of projects that seemed like a bad idea at the time and really were."
Jake: "Not unless you can name a government that would welcome such a service in their airspace that was completely out of their control"
Per the first quote, there will be plenty of us utterly unsurprised by the failure of Facebook's idiot wheeze. Because it always was an idiot wheeze. Using heavier-than-air craft for a project like this was never going to succeed economically, and was at best a borderline engineering proposition, for reasons enumerated by knowledgeable folks even as Facebook's marketurds were busy blathering about cutting edge technology and brilliant innovation—as if technology can overcome either the laws of physics or the (albeit vaguer) ones of finance. The mention of hubris has it exactly right. The Age of Stupid does seem to include some nominally intelligent and even well-educated people who nonetheless lack the wisdom to appreciate that just because something might be technically feasible, and is "innovative" (a word rendered meaningless by those same marketurds) does not mean it's either practical, or worthwhile or actually any better than tried-and-tested alternatives. While some of these bright young things may be techies who really believe they are having new ideas (and know nothing of history), I suspect that many are actually management types who fall victim to the political vice of believing their own wishful crap and propaganda.
As to the second issue, this is why we're never going to see a large network of airborne delivery drones around conurbations, and a drone scheme will always be limited to quite narrow, specific and unusual conditions where both range and property density are low, i.e. countryside/rural destinations within a few miles of a fulfilment centre. Even if government was stupid enough to permit large numbers of drones to fly over towns and cities, the whole thing will grind to a halt as soon as the first two or three people are killed or injured by falling copies of Sixty-Nine Shades of Hardback Crap. It is ridiculous to pretend that these autonomous vehicles will have safety and reliability levels similar to commercial airliners. With thousands in the air, there will be accidents.
Returning to high-altitude internet for a moment, even lighter-than-air options will need to be carefully restricted, given that overland commercial supersonic travel is likely to resume. Altitudes up to 70,000 feet won't be available if there's any chance of a an SST inhaling any kind of Loon. That said, a Loon-esque system deployed regionally and for emergencies is at least a practical proposition.
In sum, for all sorts of reasons the world urgently needs to move on from the Age of Stupid Hubris to the Age of Reflective Wisdom. I ain't holding my breath.