The NFL Draft is about the future. The ultimate goal is to project and identify prospects who will become great players several years down the line and impact winning for a long time.
With that said, it's also about the present. Although prioritizing immediate needs in the draft is often a sign of poor process, you want to select players in the first few rounds who can help your team right away. Successful draft picks provide a great deal of surplus value over the course of their rookie contracts, so ideally they'll be able to earn their way onto the field in year one and grow from there.