Much of Batman's job is getting information when he needs it, from wherever he needs to get it. The Batcomputer is a key tool to make that happen.
Outfitted with state of the art technology, and basically plugged into every major outlet in the world, when Batman needs to see something, or know something, he goes to it. It monitors security feeds, police radios, cameras, and more. All so Batman knows exactly when to suit it.
Batman can even access it remotely via his suit or a mini gadget in his belt. So he's never without direct access.