Well, I'd say it's a fact of Human Nature, but really more an effect of American Nature.
Everybody feels that, naturally, they are the most important person on the planet. If everything is not how they would wish it, well darnit, something is amiss in the universe. His Highness has not been serviced as He wishes.
"I need this! They didn't spend all their money to sell it to me, they suck."
It's like the female friend of mine that'll go into a fast food place and want a hamburger made with chicken nuggets and two slices of bacon and just -so- much mayo, no ketchup, but lots of mustard. And all no more expensive than a regular hamburger. And then takes it back if there's too much mayo.
It's a fast food restaurant. They'll try their best, but there's 15 other people in line that want their food fast and cheap and hot. You can only expect so much, but she'll bitch and complain and get really nasty about it.
When I go to McDonalds I order a Big Mac. Now, I'll take it back if they forgot half the thing, but as long as I get a Big Mac I'm happy that's what I got for my $1.25. I wasn't expecting any more. I have the same mentality when I'm going to buy game books ... sure, I might not absolutely love the way the Ranger was put together in the Core, but I'm not going to bitch and moan about it. If I don't like it, I'll change it. There's still a whole book of stuff I like, and I'm thankful they made it, and I'm REALLY happy they only charged me 20 bucks for it. You'll spend more on a DVD you watch twice. You'll spend over twice as much on a video game you play for two weeks and never touch again. That's value, in my book.
If you're not going to use Secret Product Z ... don't buy it. Doesn't mean it's bad, it means you don't need it. Great. But WotC isn't trying to screw YOU out of your money. They aren't going down the crapper because they don't produce the books YOU love. It won't be a GOOD thing that 25 people lose their jobs and no products get produced for the game for 3 years because the game tanks and is bought by somebody who will produce products YOU like. And then tanks again four months later because one person does not a market make.
We're just in a place that we can freely voice our opinions without shame or worrying about reprocussions. We don't see any of these people at work every day, we don't have to share families or friends with these people. We can say: "Dude, you suck, your ideas suck, the way you do things suck, you're an idiot." Because a guy on a message board isn't going to fire us, isn't going to neglect to tell us about a job coming up, isn't going to tell our friends at the bar that we're a prick, and isn't going to stop sleeping with us. We can tell the company that we buy products from that they suck, that their designers are stupid, and that they're just evil money grubbers trying to steal our hard earned dollar without giving us what WE need ... why? Because they aren't going to push up their glasses and say: "You're banned from the store. For life."
Now, of course, most of the time nobody is as negative as all that. It's mostly harmless complaining without any name calling and voicing of personal opinions, but people are going to say: "I don't like this thing." Because they have no personal reason to say: "Well, y'know, you rock. And this rocks. And I totally love everything you've done. I'm sorry, y'know, but I didn't really like this thing. I'm not going to buy it, y'know? But keep up the good work with everything else." We're not getting banned from the store for life if we don't include a little of the flattery that greases the wheels of Face To Face contact.
--HT