My guess is that D2D doesn't have the keys yet. Steam will treat its [paying] customers as first class. "Those of you in first class may now preload".
The rest of us (D2D, brick and mortar) will be coach class. D2D will get their keys when Steam/2K give them to them - then they call fill their database and we will have our key. I have no problem with that - I paid less and got more, imo.