When it comes to Mass Effect 3, certainly they have the right however vaguely enumerated to make what they want, and those who consume it have the right however vaguely enumerated to say that what they have done is wrong/bullshit/authentically evil. These rights dont necessarily overlap: they exist as perfect spheres, bouncing off one another in space. Creating or critiquing is just a way to pass the time until you die. I wont say neer the twain shall meet, but they might not, and they dont have to.
Ownership is a very complicated business when it comes to cultural product, though. They succeed by virtue of the fact that we, as players, incorporate these stories into our lives. Ive always wondered what the conflux of digital goods, interactive storytelling, algorithmic content creation, and democratized funding mean for an idea like authorship. I think were beginning to find out.