I don't care how technical you want to get about the definition of theft, depriving someone of money is wrong.
If someone creates and sells a software that replaces Photoshop, it will also deprive Adobe of money. It is not the act of depriving someone of (potential) money that is wrong (although it may be illegal). You don't have a "natural" right to force someone to give you money, you know, although you may convince the state to grant you that benefit.
Intelectual/Imaginary Property is a fiction. It may be a useful fiction, but as with all fictions, once you try to extend it and to treat it as reality, it breaks and loses much of its usefulness.