I have an XBox One, but you don't hear me whining about not being able to play Bloodborne.
That's not really a comparable example. You and I were aware that we wouldn't be able to play Bloodborne because it is not available for our platforms, so we didn't pay any money for it and thus are not their customers. Developers do not have any obligation to make every game available for every platform that exists, or to provide service to people who are not their customers.
DAI is a game that I already own. I paid the same purchase price as anyone else. I am Bioware's customer, and we're talking about content for an existing paid product.
A game you bought is a totally different thing than a game you didn't buy.
The specific nature of the obligation Bioware has to their paying customers is certainly debatable, but the fact they have one is valid as a point of discussion.
It will come out seen enough & then you can play it. Stop whining already! God! I swear you guys are worse than spoiled children who couldn't get the toy they wanted from a department store. 
I think a better example would be if you went to the department store, laid your money on the counter, and asked to purchase a cool new part for your toy. The store clerk says, "Sorry, we don't want your money today, you're not a preferred customer." You ask, "Well... when can I buy it?" And the clerk replies, "I don't know. Sometime. Whatever." And turns her back to you so she can cheerfully sell what you wanted and attempted to pay for to a different customer.
Is the store within its rights? Sure.
Is the customer going to be happy? Probably not, and it's not really an unexpected reaction under the circumstances. 