Batman might look like a loner, but he's nothing without his family.
Although Bruce Wayne embarked on a one-man warpath when he entered the burgeoning months of his crimefighting career, he has since gone on to foster a veritable family of his own. Even in those opening years, he relied on the help of Jim Gordon, Harvey Dent and Alfred Pennyworth, but now - more than ever - is it clear that the Dark Knight is a team player.
With over five Robins, three Batgirls, a Batwoman, Nightwing and more having joined the cause over the years, the point's been made abundantly clear that the Caped Crusader needs allies. There are obviously stories that lend themselves better to a solo format (the infallible Ego being one of them), but they've never come at the expense of Batman's allies, especially when - in some respects - they're competing for an equal footing in the spotlight.
Batman's a fighter as well as a father. To neglect that element would contradict everything he stands for.