Sony is a business and even though hacking has to be part of the reason, I'm thinking they probably were using the memory cards to try and make some of the money they're losing on the Vita itself back.
see, i don't think Sony's that stupid or greedy. I'm sure they have people there smart enough to realize that you sell less when you increase the price. I'm even guessing they have people there smart enough to realize that if memory is cheap, people are more likely to buy more games.
But... they also likely had a crack team of engineers working on the piracy issue, and I'm guessing they put forth the notion of truly proprietary mem cards that would cost more (r&d, economies of scale). I'm even willing to bet they had many meetings about the pros and cons of going with this vs. going with standardized cards, and ultimately decided this was the path to go on.
what i seriously doubt (as in, 0 chance) is that accounting called up the engineering department and said "hey guys, we're greedy -- can you develop an overpriced mem card so we can gouge consumers?" That doesn't pass the smell test. It doesn't even make sense. If they felt like they could have reasonably used standard mem cards, they would have - it would have been incredibly beneficial to them for any number of reasons, with the one big con of security holes.
So yes, I wish mem was cheaper. But I don't blame Sony. And in regards to 'making back money they're losing on the Vita', my guess is they're not making much on the mem cards either once you factor in the aforementioned issues of r&d and economies of scale. My guess is they want to drop the price on both mem cards and vitas as much (if not more) than we do to increase sales, but can't just yet for financial reasons.