These days I try to avoid having the players make such characters, for just the reasons you give. For example, at the start of my current campaign the instructions to players were: (i) build a 1st level PC who is 4e legal; (ii) your PC must have one loyalty to something/someone as part of his/her background; (iii) your PC must have a reason to be ready to fight goblins.Depends what you mean by serious about the game. Certain characters simply aren't "active" characters and are much more passive.
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Unless the DM actively gives them a quest and appeals directly to them, they will not DO anything.
The way the campaign has unfolded reflects, to a significant extent, those loyalties and those reasons that the players built into their PCs. It's interesting how the reasons to fight goblins continue to figure prominently in the game, even though the goblins themselves are mostly (not completely) out of the immediate picture now (at 15th level).
For example, one PC's reason to be ready to fight goblins was that his (former) city was razed by humanoid armies. And since 3rd level, he has been on a quest to restore the Empire of Nerath, and his city as one element of that, by restoring the Sceptre of Erathis (= the Rod of 7 Parts).
Another PC's reason to be ready to fight goblins related to his background as a dwarf. Now he is a warpriest of Moradin who is the party leader, and trying to protect the remaining settlements (both human and dwarven) against marauding armies.
I guess what I'm trying to say is that I've found that just a little bit of proactive PC background, with quite a narrow or minimal focus, can end up producing a lot of drive and (unpredictable but still powerful) direction for a campaign, once it actually gets picked up on and brought out in play. And I don't think, these days, I could go back to a game where a PC starts with nothing but stats and a tavern corner to brood in. For exactly the reasons you give.