Most "official forums" I've been on, have mostly been just for the players to discuss amongst themselves. Especially the "General" one. Vast majority of company communication on forums tends to be in the Bug Fix forum. And the "News & Events" forums for games that are online/MMOs.
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re: main topic.... honestly, I separate out how FO:NV was done, just because another company was also involved. Bethesda's mainline games haven't really had much in the way of pre-order boni. And the Team Fortress junk also seems like it was due to the tie-in with Valve/Steam. So, again, another company's influence.
But I guess we'll see. Little reason to pre-order the basic version at this point, especially digitally - we don't even have announced system requirements yet. FO4 only really seems to be up on the Steam store because it had an announced date at E3, and they wanted to take advantage of the "WOOHOO!" reaction of fans....