It is not "Star Trek XI." There will never be a "Star Trek XI." It's called "Star Trek."
"Star Trek XI" may lead to confusion, as the title suggests it is a natural progression of the other films, or that it fits in perfectly with canon, which it does not.
Edit: Calling "Star Trek" "Star Trek XI" is like calling "Star Trek: The Next Generation" "Star Trek Again," or "Another Star Trek," or "Star Trek 2," or "Star Treks."
"Star Trek XI" may lead to confusion, as the title suggests it is a natural progression of the other films, or that it fits in perfectly with canon, which it does not.
Edit: Calling "Star Trek" "Star Trek XI" is like calling "Star Trek: The Next Generation" "Star Trek Again," or "Another Star Trek," or "Star Trek 2," or "Star Treks."