I think it depends a lot on the game/on the campaign/on the setting. If the game/campaign/setting is centred on a group of adventurers that have gathered for other reasons than "let's kill monsters together" and/or if the game emphasises social interactions, a detailed background will be a necessary part of character generation. HQ2, as you have pointed out, is a good example, eg, the Startar book. I have something similar (alas not on such a scale) for my upcoming Chinese role-game with suggestions: a judge and his constables, a merchant and his bodyguards, a member of the gentry and his retainers,... rather than having it as part of chargen.
But if you're playing classic fantasy just for fun, you don't need a detailed background, do you?