What is "experimentation?"
I think it's an error to assume that "experiment" in literature means remotely what it means in science: an empirical testing of hypothesis pursuant to uncovering natural law. Experiment in science is a process, a tool towards gathering knowledge. Experiment in literature, on the other hand, is more often variations on a theme: playing with form, playing with content, playing with effect. (I use the word "play" intentionally.) It often is little more than innovation in form.
I am inclined towards categorical inclusion, rather than categorical exclusion, in creative ventures. I dislike cenorship, and I believe that the worst, most insidious, form of censorship is self-censorship. I think that creative art must retain the right to offend, annoy, diatribe, argue, disturb, and dismay. That doesn't mean I like all such artistic products; it does mean that I value their existence, regardless of whatever I personally might like or dislike about them. Freedom of speech has to be an absolute: the freedom to say what you mean, what you think, what you believe—even if (or perhaps especially if) what you say is offensive to some. The most democratic right involved in the freedom of speech is the freedom to ignore the speaker. We don't need to have the right to shut the speaker up, and prevent them from speaking out; we do need to have the right to speak up in disagreement to their ideas.
Yet I often find myself accused of being an experimental writer. I certainly don't feel that way: I just write what I am interested in writing. It's true that I do play with innovative forms: I have invented (or discovered) several poetic forms; I am a creative explorer, constantly trying out new things; I push existing forms as far as I can, to see what happens (although, even when I have labeled non-haiku as such, they often get dismissed; if I had labelled them as haiku, of course, they would have been dismissed as non-haiku: with some critics, you just can't win), or because I want to try to say something new within the existing form; I push the contents of the few forms I work in in non-traditional directions. I think new thoughts, and I express them. Sometimes I spend a great deal of time and energy in educating the audience, rather than continuing to make new work. (Explanation and justification get old rather more quickly than they used to, I admit.) My criteria for a successful work of art remains basically the same, though: did it move me? did it make me see the world in a new way? did it expand my experience, while also bringing me inside its world, to experience things from the inside?
So, is experimentation everything that is non-traditional? When a critic uses the word "experimental" in a dismisive or perjorative manner, that is exactly what they mean: this doesn't fit into the existing boxes. But "thinking outside the box" is something I would be proud of, rather than dismiss out of hand. The literary box can be confining and stifling; that's often exactly what formal innovators are rebelling against.
What of metafiction? I am generally interested in metafiction, although much of it does suffer from the tendency towards playing games, rather than providing a deep experience. Metafiction can indeed be wordplay and head-games, although at its best, it is genuinely expansive.
I am generally in disagreement with critics who dismiss metafiction out of hand, simply because it does not conform to their ideas of what fiction ought to be, or is. Borges did not write short stories, and judging Borges' short fictional pieces by the standards of "short stories," even formally innovative ones, simply misses the point. It's apples and oranges, folks.
I am even more in disagreement with critics who equate "experimental" with non-mainstream—which usually means non-marketable. The only way the mainstream expands is to incorporate the non-mainstream that creeps into view from the shadows. Most of the works of the past we view as essential classics, after all, were originally panned by the critics as useless, wrong-headed, or just plain bad.
Innovators will always have to educate their audience. It's the price you pay for reguarly thinking outside the box.