Early access was a sales point and was advertised/promised when buying so yes they have to give early access. The way their handling it on the other hand leaves much to be desired in my opinion.
Totkjal said it but i'll answer anyway..
I meant they didn't have to offer it in the first place. It's not in with the price of the game, people that won't pre order will pay the same as us so we didn't pay any more to get in the game early.
But not only was early access offered but it was increased by 2 days, yet people are whining.
If they had let everyone in and the servers crashed, people would be whining.
Long story short, people will whine no matter what happens.
Unhelpful comment but deal with it. They won't go any faster and it will just lead to people making snarky comments back at the folk complaining.