The key word there is "taking" (i.e. depriving the original owner of it) rather than "copying".
The idea that "copying" could be wrong and intangible things could be owned is a very recent one compared with the concept of stealing - and the modern concept of quick, effortless, cheap copying as something that the average person in the street (rather than a writer or publisher) might do would still have been science fiction to the original authors of copyright law.
As I've already said - its not about whether piracy is wrong, it is about how serious it is and what measures can be justified to prevent it. The word "theft" is being used as an emotive term to justify a disproportionate reaction.
You're living in a semantic world of one, methinks.
Also, that semantic world has a different history than this one. Intellectual property theft is not a new idea-- it's a concept that dates back hundreds of years. Protection of intellectual property is mentioned in the US constitution, and it certainly didn't originate there. You can redefine words how ever you choose, but you're going to have a hard time keeping a conversation.
Regarind the seriousness of the crime: they did, in fact, deprive the owner of the value of what they stole. In aggregate, the value of the stolen property is probably somewhat less than the combined purchase price because there may be some number of people unwilling to pay $5 for a game, but it had value none-the-less.
The kicker though is that they've deprived the owners of far more than the value of their stolen property. They've deprived them of the value of all the property sold to date as the refunds go out. Further, they've deprived the legitimate buyers of the surplus value they would have received beyond the purchase price, the time they've invested in the product in anticipation of future value and the opportunity to have invested their purchase price elsewhere.
The mistake you're making is assuming you can only steal atoms. Even when a car is stolen, we register the loss in dollars, not pounds. If I steal an iPad from the Apple Store, the value of the theft I will be charged with includes the labor, design, and energy that went into it as well as the raw physical materials. If I found your bank login and transferred your life savings to my account, you'd certainly call the police. Those bits in the bank computer are equally, and I'm not even copying anything-- just moving a few electrons a few nanometers one way or another, flipping magnetic polarity on a platter somewhere.
So yes, stealing different things have different magnitudes of ill effect, just like it matters which pound of flesh you choose to excise. To argue that stealing enough copies of a game to shutdown a company isn't theft, though, is just wrong.
) I doubt* that developers can design protection around it.
