I wish more people saw these issues the way that I do. There was no theft; there was never any theft. Ideas can't be stolen, only copied. The copyright holders still have the ideas she used, and nothing she has done affected anyone else's ability to use those ideas in the slightest.
Let's avoid the legal part of the discussion that Umbran admonishes for. Suffice it to say, if she broke a law, the lawyers will be happy to sue the stuffing out of her for it.
My name is on a patent that my former employer owns (meaning, I know a thing or two about IP). I design software for a living. It's all my ideas, expressed in code. While you can't steal one of my 10 ideas and now I only have 9 to sell to other people, you would still be violating my wishes and potentially reducing the value of my 10 ideas.
Firstly, there's credit that's being stolen. I am prideful in my work, in that when you know something was built by me, versus another builder, you are happier (as my customer). Therefore, it benefits me everything my idea is used, that I am associated with it. That gets me future business. If you steal my idea (and start selling your own version of it), they customer is happy with YOU, and not Me.
Nextly, I am a control freak to some extent. I don't use my front lawn for much. But I absolutely don't want anybody else using it for their dogs to crap on or some other purpose I am not aware of (like the 2 kids who were screwing in my bushes until my dog found them). I don't want somebody else taking my lawn for their own uses even if I'm not actively using it (the Mystara situation with WotC). And that is my right to do so as the OWNER.
The same is true for ideas. Minecraft (made by Notch) is directly inspired by a game called Infiniminer (made by Zach). Minecraft has made millions of dollars, Infiniminer has not. And it's not because MC stole the idea from Infiniminer. Nope. Instead, Infiniminer died because other developers reverse engineered the code of Infiniminer and began making their own variant versions. Thus, the dev couldn't establish his own work as the definitive version, so he gave up. Once Infiniminer died, Notch was a fan of it, and had new variation idea on the general concept. Unlike Ms. Alley, Notch had the courtesy to code his own version from scratch. Had this theft and forking of the code not happened, Infiniminer might have evolved into Minecraft and Zach would be rich, instead of Notch.
http://www.rockpapershotgun.com/2011/01/20/proto-minecraft-abandoned-due-to-epic-error/
once, as a young lad, I was making a game called Arena. This was in ye olde times of floppy disks and Apple IIe's. It was coming along great, and my friends really liked it. One of my friends who also programmed borrowed my disk and copied it. He then begain making his own changes. this was NOT a good thing in my mind. I tossed a magnet into his disk case to take care of the problem (back in the day, one carried your stack of disks in a plastic box that fit in your backpack).
I wasn't sitting on the goldmine that was Minecraft (after all, you've never heard of my game). But I knew that I would lose control of my audience and my product if I let rogue variations develop. It was non-trivial to write code back in those days. Even harder to integrate changes from another developer into a common code-base after the damage is done.
Whether it be a real physical property or just bits of magnetic pattern on a disk, the guy who owns it is protective of it. It hurts him emotionally, economically or physically. It don't matter what the thief thinks, it's the Owner who matters.
I hope that this gives some perspective on how an Owner feels. Even in cases where money isn't involved, if you take my idea, that makes me mad. That's harm. If the owner gives his idea away (like Zach effectively did, AFTER the theft), that's his choice.