Interactivity is the right word, not Linearity.
A good story will be a good story no matter what, but JJJ is right -- this is a CYOA-based site, so having interactivity is important.
Your stories (the Dark Tales), for examples, have very few choices, but I enjoyed them a lot. In fact, I'm very saddened that you deleted them -- those were a great asset to the site. I think if you added some trivial interactivity (like, a waitress asked what to order, and you gave a choice), they would have received better feedback from others.
I think this may be biased, but look at THE PROPOSAL -- the purpose of that is to tell a real story, and b/c of that, there can be only one ending. If you go through, all the interactivity in the storygame is entirely trivial. But (I think), it still makes it feel like you have a choice.