I disagree. Your analogy doesn't work. If you took DOOM, re-created the graphics in slightly different colors and styles because you didn't want to get sued for copyright infringement, but implemented the exact game mechanics, the story, controls, and all of the major concepts of the game, and called it FLOOM, you'd be crossing the line in a way you are not by simply creating a search engine.
This is basically Zynga's methodology for creating products that they've clearly used a number of times with clear evidence. I don't think they see themselves in the business of designing games since they leave that to the companies they steal them from.
I think it's a false dilemma to say that we shouldn't criticize Zynga for this because it comes at the cost of being able to criticize them for other reasons. For some, this is just as an important reason (if not more important) than the ones you listed.
This is basically Zynga's methodology for creating products that they've clearly used a number of times with clear evidence. I don't think they see themselves in the business of designing games since they leave that to the companies they steal them from.
I think it's a false dilemma to say that we shouldn't criticize Zynga for this because it comes at the cost of being able to criticize them for other reasons. For some, this is just as an important reason (if not more important) than the ones you listed.