Probably because they are trying to leverage the oldest remaining inventory to up this quarter's numbers, while Grapes and other spring releases will see restocks in August/September. It's hard to tell though how much this is a cohesive plan between Nike and its partner retailers, and how much of this is inventory that retailers are receiving from Nike for the 5/25 date. Is it some of both or is all of this inventory coming from Nike?
What's clear is that you can now expect massive restocks (compared to the past) on a quarterly basis this year - and likely moving forward until the Jordan craze dies down. I might scoop a couple on 5/25, but just confirms that anyone with a brain should avoid resellers trying to ream them and just have patience knowing that there will be multiple opportunities in the future for most releases, online and/or in-store.