I've remained on the sidelines, watching the commentary on this topic, and it occurred to me that it really boils down to one simple concept folks, and lessons you were taught in kindergarten.
First and foremost, this is a free community, and by "free", I don't mean monetary. I mean "free", as in every single post made by members is done voluntarily, as are responses to PM's. There is no inherent obligation for anyone to participate, post, answer questions or frankly, to log on to begin with. So, out simply, check any sense of self- entitlement at the door.
Secondly, in kindergarten, you were taught basic manners and standards of social behavior, including the concept of thanking someone for doing something nice for you of their own free will, being under no obligation to do so.
So, apply principles number one and two, and everyone is happy. Those with needs have them met, and those that meet them come away feeling appreciated. Where I come from, that's a "win / win" formula.