I do think retailers shouldnt be doing drops for every tiny little shipment they get, probably should wait until at least a 1000 or so are available, they also of course should be doing back order queues etc. but wont.
Unfortunately they won't do that when they can do a limited drop, sell out in minutes and generate loads of website visits in a day.
Sitting on stock isn't the answer either, as stock is so few and far between they would be sitting on it for weeks/months.
It's not hard getting one currently, managed to get one last week without to much of a problem just had to be quick. It isn't an optimal way of doing this though and I think lessons may be learned for next console releases.
End of the day what ever system is in people will find a way to complain, if it's register with the chance to buy complaints will be on how random it is and how it isn't fair. If backordered then people would be moaning about how long they have to wait considering they have ordered etc. With the current method, it's complaints about how quick they go.