You're using comparisons with other bad things, as a way of making a bad thing ok.
Other bad things should be good
Seriously, this is pure greed. You can either support it in gaming or go against it.
Personally, I think greed should go facilitate itself somewhere outside my beloved gaming hobby, but I'll live.
However, it comes down to this:
If Deus Ex: HR feels complete and wholesome without the preorder crap, I'd be fine with this. If it turns out they actively remove from the original design, and sell pieces of the original vision "on the side" - they're part of the ongoing trend of breaking games for profit. If that's "ok" to you, you should perhaps follow that trend and line of thinking to its end, and imagine what games will become if we accept it - as consumers.
Personally, I think preordering should never affect the gaming experience. Simply set the price point lower - and people can decide if they want to take the chance. That's MORE than enough incentive. People don't need more incentives. If the stores want to play hard-to-get, we should show them that the digital download option is the natural next step in this gaming industry. There's no way around it, anyway.