It really isn't. People get so upset over OPTIONAL things, it's ridiculous. No one is forcing you to download any DLC or pay for microtransactions. None of it.
You know what I do. Sit back, think "Is this worth the money to me?" If so, yes, then I'll buy it and give the developers some extra money for their hard work.
All I'm saying is that if you put "I don't like retailer specific preorder DLC" as an excerpt in your book, it would make for somewhat uninteresting reading.
It's not really an extreme thing to say.