i see what you did there

it doesn't mather if you call it a bonus for preorders or a punishment for non pre orders, it's the same.
I have no problem with an icon for preorders, but things like this:
For example, we plan to have a certain sub-forum which only 'true fans' of our internal titles can access where we'll let those people have a larger input on what we'll focus on for further development during the earliest part of the game's life-cycle. Of course, there'll also be a special icon indicating that you're a true fan, as well as unique avatars.
first off all you disencourage people who haven't preordered the game to buy it, 2nd you call everyone who hasn't preordered not a "true fan", there are people like me who have been playing paradox games since 10 years and i feel a little bit of a 2nd class customer when reading that, 3rd. why is there a difference if i buy the product on day1 or if i preorder it, you get the same amount of money, you should at least give all the so called "bonusss" to people who buy it in the first 1-2 weeks.
Lack of a bonus really isn't the same as punishment, it's just not. I don't feel like this is something that needs explaining, so I am not going to argue about it beyond this post, but if you buy X and receive X+Y, Y is a bonus. If you buy X and just get X you are just getting exactly what you bought, you are not being punished.
As regarding the rest of your post:
There is no other forum, that never happened.
No one has used the term "true fan" since that rather old post. I agree it's not a good term, but it's fairly moot at this point.
Icon + avatars is a forum bonus only, and in fact we DID give it to everyone who registered in the first X days after release, not just pre-order people.
In (very)short, day1 sales are more useful as it put you higher on stuff like top sellers lists sooner, which leads to more sales as more people hear about it/assume it is good if it is selling well etc.
Honestly, if anyone is discouraged from buying CK2 due to not getting the forum gold icon, I'd say just don't buy it, it's ok. I'd much rather people bought our games because they want to play them, I'd feel rather bad if they were just bought and thrown away to get a special forum icon.