Because you cannot be an outside eye on your own process
Because if you know the ideology, aesthetics and interests of the outside eye you can also
choose to ignore it.
Because the outside eye can question, confront and clarify weather or not your
performance produces what you which it to produce.
Because when you think about the outside eye, you force yourself to think in terms of
presentation. It is not what the outside eye says about what you present but more the fact
of presenting it in itself that produces an effect.
Because your audience in the end will be a bunch of outside eyes.