While I agree to a certain extent with what you've said here, my mindset is, all too often you see one of three things precede many of these games before they are abandoned it seems like.
1) The game does well enough monetary wise that earlier updates that were being put out at a much higher frequency before, starts slowing down dramatically to the point where any type of update that may be put out gives the impression they are just milking the system at that point.
2) The developer starts actively arguing with its game's followers when they start requesting changes, arguing that the game is their creative vision and when some players start indicating "the game could be so much better" if the developer would just listen to and implement the changes being requested, the developer starts taking things too personally instead of just brushing them off.
3) The developer starts pandering to requests from its player base looking for what they would like to see ultimately, and while the the developer is initially receptive to this, often times starts to push back that this was not their vision for their game or getting sidetracked by each and every one of these requests and starts implementing them into their game partially but then never fully completes them before starting to implement yet another requested change.
It just seems like to me, many of these game creators may be getting overwhelmed with the scope of the project their game ultimately take on but at the same time, many of them can't handle the criticisms that comes with being a creator and making it public and then once enough negative feedback has been reached by them, they enter a shell and retreat. It's like many of them only expected positive reinforcement for their creation unrealistically. To me, not enough of them have thick enough skin, if you will. That it wasn't just the sheer scope of their game that overwhelms them but feedback about their game removing the desire to follow through and complete it for those that do enjoy it.
I agree that most devs are probably way in over their heads. However, I don't believe that most go into it expecting positive reinforcement, I think most think they have thicker skin than they actually do. You have to realize that the stresses you're exposed to, especially those related to performance inadequacy and creativity, is relatively infrequent and smaller in scale in the average person's life. You might go into it thinking it'll be like 5x harder than what you're been facing, but it's actually 20x harder, or even more depending on how popular your game is.
1) Game development generally isn't linear. You might have a clear idea of what/how to implement something up to a certain point, and have visible work to show for it, but you eventually hit a point where you need some time just to lay the foundation for the next set of work you need to do. It could be anything between the chosen game engine's limitations, game balancing, creative blocks, or lack of foreknowledge. Sometimes there's backend stuff that a dev needs to handle before visible progress can be seen, but a lot of folks in these forums either don't understand that or choose not to acknowledge it. And it's undeniable that some devs are actually milking, but those accusations probably don't affect them as badly as it does people who aren't, because it signals to them that people have unreasonable expectations. And when people give you unreasonable expectations, you generally quit.
2) I think most people don't really have the kind of thick skin to take constant criticism, but it's not something you will into existence. It's a skill you develop from exposure, and it's the overexposure that kills you. Think of it like exercising and pushing past your limits into muscle injury. To heal, you'd need to either take a break or work at a significantly slower pace. How badly criticism fucks with your head isn't voluntary. Criticism feels personal because it's a personal effort. You're not doing it as another cog in the machine, you're doing it using all your wits and skills. If you work in a large company, there's a number of people you could blame, like management, or that one guy who never works well with anyone, or the shitty software they've given you to work with, but there's no such escape when you're every role at once. It's hard being told that you're doing less than your potential when you're already trying to give your all and have been for a long time. You can argue that a dev should be more professional in how they conduct themselves, but they're only human too.
3) In itself, I don't see anything wrong with asking the the audience what they want to get out of the game. Ideally, what happens is that a dev weighs the resource cost and intangible payoff to these ideas before deciding on the order of priority. What I suspect usually happens is that the dev starts with what's easiest (or at least what they think is easiest) to do, and then proceeds to fight an uphill battle as they work on increasingly difficult tasks. They might feel pressured to have something, anything to show for their effort (because that's what the loudest voices are demanding) and sucked into a cycle of doing the easiest part, stopping when they hit a dead end, and starting something new in hopes of making headway. It's simply hopeful thinking. When even that fails, all you have left is hopelessness and abandonment starts to look really good.