Well not as many artists as you think, it's a very saturated and competitive market where only the top artists with the most flexible acceptance rate for kinks do well, though he looks talented enough to be there.
But yes, getting flak certainly wouldn't keep anyone's motivation up. However, it's still partially his blame. This is like kickstarter drama. You have to understand if people give you say $500 over time adding up among multiple people to like half a mil to make what looks like a really cool survival horror game, and then you abandon it and say you're going to use that money to make a minecraft clone instead, well...
Yeah people are going to be upset. Not even a new concept, because it's happened a lot before and is partly what killed crowdfunding (along with so many of them becoming effectual scams) and why few major games use it anymore.
That doesn't mean the dev deserves to be treated like this, but the anger shoulda been anything but unexpected. I guess it hurts even more when the abandoned game really had potential.