As a Junior Creative, there is an inverted relationship between the amount of time spent concepting vs. the amount of time you'll spend executing someone else's concepts.
Coming right out of school you'll be incredibly lucky and downright unique if you land a job where you get to concept all day long. Perhaps 5 years ago when agencies were fat and happy with meaty AOR accounts this may have been the case. Today, when creative departments are integrating and streamlining (ie downsizing), every body counts. You must be able to execute and by that I mean be able to design and layout another (more senior) team's ideas.
Lately I have been reviewing junior books that are way too heavily focused on conceptual work and painfully lacking in design pieces. This balance is quite OK for mid- and senior-level creatives who spend more of their time concepting projects. But for juniors, not so much.
Sadly, I think your school instructors focus on concepting to the exclusion of design and, in my opinion, that hurts a junior portfolio. If you can't display a command of type, execute in a variety of styles, and show me you can work the software, then why in the heck would I want to hire you? I cannot afford to have juniors that lack these fundamental skills.
You know all those school projects that seem boring: logos, CD covers, identity systems, packaging, menus, invitations, etc. Those are exactly the means by which to show off your design skills. Don't discount their importance in helping someone judge your creative ability. And if you can throw in a couple of strong and smart conceptual pieces on top of that, you're golden.