A portfolio is, unfortunately, always primarily about showing one’s most aesthetically pleasing work. I might get arguments on that, so I’ll explain. Portfolios provide superficial glimpses into what designers are capable of producing. They don’t typically delve deeply into the details of how the work came to be, the thought process that went into it or what obstacles were dealt with and overcome.
When presenting portfolios in job interviews, designers have the opportunity to tell a story or two about the work. When seen online without the benefit of the designers’ narrations, portfolios are little more than a series of images. Viewers spend a few seconds on each, making judgments on the aesthetics and shallow assumptions about anything deeper.
The only way you’ll ever have authentic narratives to tell about your work will be those you obtain through actual experience. They can’t be adequately simulated, as you proposed, through a reimagined campaign redo from someone else’s real-life work. This first-hand experience is why it’s so important for design students to work part-time in internships while still in school; they augment the academic learning with the day-to-day realities of the business of design.
None of this is saying that you can’t be aware of these things when starting out. You should certainly be prepared in a job interview to discuss your thought processes and reasoning behind your student work. The more you can do this in the context of how your work might be applicable to business situations, so much the better.