There are lots of different contributing factors to the studentyness of a book. For this post, let me just bring up one: Most studenty books neglect calls to action.
For those of you unfamiliar with the term, a call to action is something that gives the reader, viewer, participant, whoever, something to act on. It could be as simple as a website or phone number, or as specific as a date and location. It doesn't have to be crass like "Hurry! Limited time offer! Call now!" (In fact, if you're considering that kind of copy, you might be reading the wrong blog.)
Maybe you buy the argument that a lot of advertising is about brand building, or having a conversation with the consumer. I buy that, too. Sometimes. Nike rarely uses a call to action unless they're trying to send you to some kind of microsite. iPad commercials don't end with "Visit apple.com" popping up at the end. But for most ideas you're going to present to your client, you're going to need something more than just a logo. A book entirely full of pure branding pieces comes across as a very studenty book.
Look at it from a client's point of view. You're paying your agency to come up with a great idea and execute it. You're paying your media company hundreds of thousands (maybe millions) of dollars to make sure people see/hear/experience the idea. You've got a boss who's expecting you to deliver some kind of tangible results. And you're going to run an add that hopefully gets people to think of you as cool?
You don't have to slip into gross promotional language. Just figure out what you want people to do once they come in contact with your ad. And then give them a way to do it.