I personally think your removing of the license was very preposterous. This things need to gain some momentum.
MIT is not suitable for a book, I think you need some kind of copyleft license (possibly with a clause) so you still hold the right to publish and sell the book regardless of contributions. I encourage you to consider opening the book for contributions. At least for proofreading it could be very useful. Personally, I like doing small fixes on docs while reading them, and if you encouraged that this would be a great benefit for the book even if the amount of contributions were small.
