Thank you, everyone, for helping make a very interesting and well thought out thread!
A few observations:
First, I find it somewhat amusing that we're talking about electric airplanes with autonomous flight, considering that the most popular means of creating sparks for aircraft engines are magnetos (two, because just one and a single spark plug for each cylinder isn't reliable enough) and the standard method of achieving fuel/air mixture is a carburetor.
Yes, yes, I know that it's effectiveness over efficiency, but one would think that both systems would have been relegated to nostalgia about thirty years ago.
Second, the affordability question is a bit like the Interstate answer; we're spending money in ways we didn't before that cut into disposable income. One just didn't have a cable bill, an Internet bill, or cell phone bills - all of which are pretty much mandatory today. Yes, there was a phone bill, but so long as one didn't call long distance (!) it was dirt cheap. The baseline cost of living has gone up with the services we now consider critical for living.
Third, the romance has gone out of flying to the general public. Then again, most of the more pedestrian pleasures of the past have been dismissed - the slow Sunday drive just to see the sights just doesn't happen, for example. Who wants to canoe down a lazy stream when one can zip along on a jet ski? Airplanes are great big things one complains about having to wait to get on with bad food (if there is any) and not worthy of dressing any better for than a three o'clock morning run to WalMart. Airbus was quite accurate in gauging the public's perceptions in naming the company.
Small, personal aircraft in the General Public's view are only mentioned when there is a crash, and when they are portrayed in popular media almost always have problems. Even in shows where the intent is to display the positives, the negatives always get the spotlight (Flying Wild Alaska, Airplane Repo) at some point.
So where does that leave us? I've said it before, but I think General Aviation is regressing back to the 1930's, where one was either very wealthy and buying cutting edge stuff off of the shelf or turning a wrench and doing it themselves. Except a lot of that wrench turning (and rivet making) has become pretty darned expensive with the demands for ease of building and a sense (and record) of safe, proven design.
The problem is that today's generations* aren't keen on wrench turning. The narrative of computer design, automation, and component replacement versus repair has overwhelmed them. Most young people today can't drive a manual transmission - thinking they would change their own oil on their cars is asking too much of them. Yes, this is an unfair generalization, and there are loads of young folks who can roll up their sleeves and fix things, but in the main (especially with urbanization) it holds true.
To think that they'd accept a bunch of papers with plans on them and start to cope tubing with goal of building a flying machine is simply asking too much of them. The blame lays with us for giving them everything we never had at the expense of our knowledge and experience of what we had.
There is sunshine, though. In dealing with young people I'm finding that they're open to learning and while with a different approach, not adverse to adventure. I was talking to a 20-something the other day who asked what the point was to having an airplane that doesn't really go anywhere (having been taught that airplanes are just transportation), and I asked if they ever water skied. Yes, they had. "Did you go anywhere?" And a light bulb moment. When I told them that my pilot ticket cost me less than six grand and the aircraft less than fifteen, suddenly aviation didn't seem so outrageous.
* Stutter implied.