I had no idea I was good at writing software until, on a lark, I enrolled in a Computer Science class at Tulane University in 1975. So I'd say, looking back, that was a good thing. If it worked out for me, why not give it a shot.
But programming is at one end of a spectrum. It's like mountain climbing or spelunking, not like bungee jumping or hiking in the Alps. Programming is hard. And it's definitely not for everyone.
I think the reason well-intentioned programmers get irritated by the sudden rush of people like Mike Bloomberg who breathlessly exclaim that they're going to learn to program, is that it's disrespectful. This is something programmers learn to live with. Because we know how the machine works, and most people don't, they don't like to listen to us. Even when we're saying sensible things that aren't very deep or technical. Just listen! thinks the programmer, knowing that it won't work.
The thought that anyone could do it and it would be a walk in the park is just one facet of disrespect. When a skilled guy like Jeff Atwood, who has created some great software, blows up over this, that's what's probably going on. I feel the same way, yet I am an advocate for demystifying technology, for removing techies from the clouds, bringing them back to earth to inhabit with the rest of the mortals.
We need to strike a balance. If you're going to learn to code, it's going to be hard. But if you're going to be a great programmer you have to start somewhere, and like home people relating to tourists, we should encourage it.
But it might be more useful if more people attempted the equivalent of the hike in the Alps instead of trying to scale Mount Everest or even McKinley.