Well, I wasn't referring to this pre-order bonus in particular, just the general practice. Not to mention that time-exclusive content is not new. For example, some kid who gets GTA V for Christmas has already missed out on a ton of time-exclusive content.
My larger point was that early adopters tend to get rewarded, no matter what the medium, just because you put your money where your mouth is. These guys that are all, "Oh, I was on the fence about this game, I'm the biggest Hitman fan in the world but game devs are greedy money-sucking leeches, so I wisely withheld my gaming dollar until I could get it at half-price."
Now they're all, "Wait, there were all these fun and exclusive missions you guys were playing all this time? Why can't I play them?" Well, duh. That's the price you pay for waiting for a better deal.
It's like showing up to a barbeque a couple hours late, because you don't know the guy hosting it, only to find all the steaks are cooked and you're stuck with some burgers and hot dogs and leftover potato salad. What did you think would happen?