I think most of the moral dilemmas that would come as a graphic designer would be issues of company management and corporate sponsor. Sacrifice of your artistic license, etc.
It's probably not too different than any artists job. There always comes a time when you have to make a decision to choose either to get the job done, no matter the cost (giving up your freedom of personal expression) or hold the high ground on your principles of the love of your art, risking your position with a company.
Moral dilemmas in matters of art I think are based more on what you feel you want to accomplish with your work, rather than doing the work. They have the starving artist cliche for a reason.
I'm not a graphic designer or anything, but I'd say that idea would be a good place to start as far as writing something up on that subject goes. To get the maximum sale, or to get the message across.
“This body is not me. I am not caught in this body.
I am life without limit.”