It's the excitement of the draft - a draft pick is like Christmas morning as a kid for some people, myself included, while I'm not a 'draftnik' I do love the draft and it's disappointing if you (your team) isn't a player. So there is that aspect that you are missing out on something. But I'm still OK with using a draft pick for a still young, room to grow, but already established in the league player I'll really worry when we start trading 1st round picks on older/declining players.
Only other difference I can see is the cost standpoint - if your top 5 players on the team are all veterans on big contracts your roster has less flexibility but if 2 of the five are on rookie deals you have extra cap etc..