Pretty sure they knew there would be backlash no matter what was done.
1. Stagger invites so that the number of angry people slowly goes down as time goes on
2. Let everyone in, potentially crippling servers (too many people in starting zones, etc), causing service black/brownouts and generally spotty play
Personally, I think the right choice was made; it won't be too long before the angry masses number fewer than those that are happily mainlining their newest gaming addiction.