Telengard
Arcane
Marketing. Getting a new name (IP) out there into the public consciousness is a difficult task. Were they to makeWhat I'm a little curious about is why was Bethesda interested in the Fallout IP for an open world RPG? Like, Fallout 3 has nothing in common with its predecessors and it's not like Fallout 1-2 had such a huge following at the time. Why didn't they use another IP or even come up with their own?
Nab Fallout, and you have instant "Fallout revival" news stories for the first run of adverts, all free. All the Fallout fansites are already stumping for you, even if unintentionally, since they're all praising the Fallout universe. Someone googles Fallout, and it's all good stuff, none of it paid for to be there by you. Then a portion of the Fallout fanbase will start stumping for you for free, because they're such Fallout fans and so excited to have the series back from the dead*, which is better than a marketing department, and also free. Plus, even if it later becomes apparent that you crossed them, you were never making a game for them anyways, so it's not like it was lost sales, and all the free advertising is already out there - with late badmouthing by such a small group having no way of catching up to all the good press now out there and out there first.
As long as the IP is relatively cheap, it's win win from a publisher perspective.
* and because they're so gullible