Detailed backgrounds have little relevance in the games I've played or the campaigns I DM... at least at the start of play. I do insist on a few words describing the general demeanour, outlook, and attitudes of the PC, and whatever has happened in their past which might have influenced them, as well as at least one player-created plot-hook. That's it. The rest of the character is built during the actual game and if a player wishes to drop a new piece of history in later-on, that's fine, within reason.
I can certainly see how detailed backgrounds may help a player more fully realise their PC during play, and will enjoy anything my players can come up with should they feel so inclined. I've never seen the need as either player or DM, and I don't think my own PC's have suffered for it.