I recently read Motivating Students with Teaching Techniques that Establish Relevance, Promote Autonomy by Katherine Robertson, PhD and I agree that students are more motivated when they can see how completing a class assignment will serve them well in their future jobs. I was in graduate school until fairly recently and the projects I was most excited about and enthusiastic to do well in were those that I could meld with an actual need at work. It is kind of like when students ask if they will be tested on a topic - if they don't see a future application, they won't feel like they need to attend to that information.
What this may mean? Well, like in the article, some course requirements may only need to be renamed to reflect the real world relevance. This should be a fairly simple fix - especially if great pains were taken to have meaningful homework in the first place. If you cannot explain why the homework is important to their future work, then maybe it is time to re-examine the purpose of the assignment.