I'm not sure I get "Pre-Orders". Consequently I usually don't do them, regardless of special digital trinkets thrown in or not. In this day and age where most games are starting to go to digital download, it's not like the game store down the street is going to be running out of copies. In fact - some game stores are not even stocking games now-a-days because of Digital Download. Which kind of kills themselves off .... but that's a whole different discussions. But it's not like ... "OMG! I have to Pre-Order something cause they are going to run out of copies!"
But, if one really wants to do that pre-order stuff and get those things that is perfectly fine. You get some nifty things for your characters ingame to show off. It's not going to hurt anything really.
I'm just saying, the whole "Pre-Ordering" concept is kind of silly. It dated back to really old times when games did come out in cardboard boxes and disks and sometimes a game was so popular the store did run out of copies. But in this day and age, it is not really necessary, it is just marketing. Oh and before the BW and EA haters jump on it and say "OMG they are so piggy" Blizzard does the exact same thing.
nowadays, preorders usually come with preloads. in other words, you get to download your game while the "traffic" is less congested, so you get to do it faster. its not that much of a difference if you don't care about playing right away, but for some people it can make a difference, not having to leave their computer downloading for an entire day, because everyone else is doing it at the same time.