A lot of the discussion here harkens back to Sony's consumer products and the BMG rootkit fiasco.

Ever since Sony purchased Capitol Records, they've had a conflict of interest that has degraded their audio (and now video) recording products. The use of DAT for music (in the consumer equipment) was compromised by early DRM attempts. The MiniDisc recorder format not only had a generation counter, they stopped making it possible to get a clean digital transfer by removing the optical outs very early; the USB transfer mechanism was DRM encumbered, making it impossible to make a digital transfer from a live recording to CDR or MP3.

This is just a sample of the marketing stupidity that Sony has shown. They have good engineers, it seems, but these engineers are forced to degrade the consumer products because the music and entertainment division is averse to anything that might allow someone to "pirate" their IP. (These folks seem to consider "fair use" to be "piracy".)

As for the current case, this time it's a aggregiously bad choice of technology to serve a purpose that is, in itself, not against the best interests of the customer.

My guess is that their software team is not very good at predicting the consequences of their design choices. They knew how to do it (hide the directory with the data they wanted to protect), it solved (protect the data) the problem they were asked to solve (actually, it didn't solve the problem, but they thought it did), so they did it that way. This was probably not even cleared by upper management or legal; they just did it and nobody within the organization objected. "This is a technology so powerful that it can only be used for good or evil!"

Unfortunately, this sort of short-sighted thinking is common (if not dominant) in the current software development world. Usually, it simply introduces security or performance problems while the defective software is being run (or at least installed); in this case, it enables other software to leverage it's defects without ever even being present on the victim's system. Bad oversight, no cookie, and no trust from people like us.

It's not so much that Sony doesn't learn from history, it's that they're unable to see analogies, so nobody at Sony even made a connection between the two bits of software until someone pointed it out to them.