I completely agree with you. The Dev is the one who tells his story, it's his game, and we decide whether we follow him or not. We have to let the Dev do what he wants to do, and above all that he likes.
I don't know about these game developers, but I do know a LOT of professional writers (particularly in the Sci-fi, Fantasy and Mystery fields, both in print and on screen) and they tend to avoid using unsolicited blind suggestions. There are several reasons for this, among which is "It's MY story, Dammit! If I use your ideas, it's YOUR story." (slightly paraphrased from Harlan Ellison).
Another very valid reason is that there are many instances of a author using an idea that someone sent them and then getting accused of plagiarism, and even sued. That's why many authors nowadays use third parties to read their fanmail. Even if they came up with the same idea ON THEIR OWN, if it can be shown that they even only just received the idea, they can have suit filed against them. (It doesn't mean that the plaintiff will win, but suits of this sort are long, expensive affairs.) I know of more than one instance where the author actually CHANGED the story they had originally planned because someone had sent in an idea that the author had independently intended to include.
Hey, I post my share of suggestions to devs here myself. But mine are usually only general suggestions of basic concepts that might be included. If someone actually uses one of MY ideas, the only thing that I ask is please give me a shoutout in the credits, so I can use it in my resume.
Reporting bugs or story flaws is a completely different matter, of course, and most writers actually do WANT constructive criticism.