As long as we can see what free agents will be available, before the draft, then this is good. Otherwise, you're drafting blind for a position you might be able to fill through free agency. Think about it, if a team knows it can sign a FA to fill their spot at say, right tackle, they won't spend a draft pick on a right tackle.
Actually the period between February and April is Free Agency and most of the big issues are the restricted Free Agents. Take for example the Jets this year. They lost Coles to the Redskins and reicieved the Redskins 1st round pick in the draft a few weeks later. The whole June 1st thing is for Cap issues, I believe it's something like releasing certain players after June 1st save you some cap room or vice versa. I don't rightly remember at this moment.