Weird.
I was just looking at the same information at the same time you were posting this.
GMTA apparently. I share your reasoning that it must be an important book if Jude quoted from it though I SUPPOSE I must admit there is a SLIGHT chancce as breakfast pointed out the JWs and Fundies believe.that...
Just because it LOOKS like Jude is citing the book of Enoch, doesn't mean it is. There could be another source that both Jude and the Book of Enoch are both citing separately.
What I find interesting is that the JW position has always been the nephilim were angelic/human hybrids. The bible doesn't specifically say so...though Enoch does. So in this case it appears that there must be some "accuracy" to the book.