I believe full payers were fulfilled first with Batman. SS Alex mentioned they just decided to let flex players get Supes first this time and I think the first shipment coincided perfectly with the first flex pay date (April 10th). Maybe they wanted to change it up and just let a different group receive a product early.
To me I don't understand the impatience of everyone. I've gotten stuff early, gotten stuff late, but in the end I still get it.
The only valid argument I've read about being in a later shipment as a concern is in regards to replacements. If this is your main reason, then I see your point. As with Batman, the later you received yours and had issues, the more difficult it was to get him corrected or replaced (from wait time to non existent parts available anymore).