Amazon seems to be slow in filling pre-orders, often leaving buyers waiting when everyone else has theirs. I stopped when they cancelled my pre-order for a new DSLR model that I had ordered the first day. They waited a month to do this, and said they had a error in the listing, but I could re-order and go to the rear of the waiting list.
Honestly, I've never experienced this from Amazon, and actually have received numerous products (actually delivered to me) on the product release day. I do know each retailer is given an allotment of X bodies on launch day. With Amazon being the biggest and most well known, I can certainly see how those farther down the pre-order chain can get burned as their allotment is quickly depleted. And I know one bad experience can spoil one's opinion forever. Like I said, I'll never use BH again. Seems like we've all been burned at one place or another.
I guess if you ask around enough (especially on the internet), you'll find enough horror stories to tarnish every retailer out there.
PS: I certainly agree with you regarding the use of credit cards for preorders. The amount of protection provided by a major credit card (AmEx, Visa, MC, etc.), and the cardmember warranties (ie, refunds when retailers won't grant them), are well worth any yearly membership costs.