Yes, it certainly does! Shakespeare wanted us to know right from the start that Hal isn't as dissolute as his companions; otherwise we'd lose sympathy for him rather quickly. It's the same reason Falstaff is given so many unpleasant qualities, to distance him, to make his rejection and death more tolerable (except that it doesn't quite work for Andrew!). Also, without knowing what Hal was up to, the audience would find his transformation from Bad Boy to Good King too unmotivated to be credible.