All this talk of logos, identities, branding. The words have been used so much they hardly mean anything anymore. So do you really need this stuff? Short answer? Yes.
At its core, having an identity just shows who you are to the world. If you are in business, that's kind of important. Imagine if Starbucks (love 'em or hate 'em, they are a good example) had a different logo, different typeface and color at every store. How would you know you were really at a Starbucks and not some crazy knock off place?
You want people to find you, remember you, and return to you for whatever it is that you do. You wouldn't change your phone number every day if you wanted people to call you, would you? There you have it. Get branded.