doubly so because it's not really a "book" it's just a ...booklet? guide? with 13 pages (one of which is installation) and none of them are particularly long.
Just curious why you think so. Bash manuals tend to be pretty long and it seems they also provide a quick reference for commands right in the same docs page. Is it the "book" aspect of it?
Because a book is a big upfront cognitive investment - and if it's written well, it will begin with the assumption that you already want to use Nushell, because why else would you have the book?
If you want to entice users, they need to see something immediately valuable, and it needs to come with essentially no investment on their part.
That... is not a good way to entice me to try something.