It is a marketing ploy, but, well, there's nothing inherently wrong with that- Don't get me wrong, Companies can certainly cross liens with how they release things, but Midnight releases are just hype building, and hype building is just a scaled up version of what merchants have been doing to make a living since humanity began using arbitrage. I certainly don't see how this is hugely different from the Gencon pre-releases FFG has done in the past (Yes, there might be a little buying blind element, but that's true a lot of the time when buying a new release)
If you don't like Midnight releases, don't go. I generally don't go to midnight releases unless the event is more than just buying product, like, say, Magic: The Gathering Midnight Pre-releases (Which are sealed tournaments).