Obviously the content producers have considered doing away with release windows, and for now have chosen not to. Its safe to assume they've decided they'll make the most money this way. So why? That is a much more interesting question.
Some things to think about:
1) iTunes/Amazon/Google pay the content producer each time they sell something (basically consignment), instead of making a big purchase upfront and then reselling the product (like DVDs, or even Netflix). The DVD model seems much better for the content producer, as the DVD saler is taking some of the risk whereas iTunes/Amazon/etc assume none of the risk.
2) Cannibalization is a bigger issue than we might think. Streaming with no release delays is basically an a la carte model. Its likely this would reduce the content producer's total take.
Chris Dixon has a great article on why bundling can be a win for both sellers and buyers here: http://cdixon.org/2012/07/08/how-bundling-benefits-sellers-a...
3) The author is probably overestimating the increased sales generated by an earlier DVD/streaming release.
4) Not everyone is willing to pirate content, simply because it is illegal to do so. For some people, not being a thief is more important than seeing Homeland Season 2 right now. Thus the growth of piracy may be limited in a way the OP does not understand (not by viruses or technological hurdles, but just because some people don't want to be pirates).
Perhaps there's a model where simultaneous releases do make more sense for the sellers. I'd certainly welcome it. But its not obviously better for the sellers, and protecting your revenue stream is not equivalent to being stuck in a "wasteful rear-guard fight for the preservation of an analog era relic", as the OP claims.