It is not included in the Bible we have today, but there's a good reason for that. It was completely unknown prior to the KJV Bible and all of the pre-KJV translations and collections of scripture, so there could be no way for it to have been included in the Bible we have today. They did not have a copy of it to include in the compilation of the Bible, even though it is quoted and mentioned many times, so it was impossible to include it at that time. However, when they created the Canon of Scriptures, one of the criteria they used for inclusion in the canon was; Is it mentioned and/or quoted elsewhere in scripture? Enoch meets this criteria.
The book of Enoch was well known and very much discussed for inclusion. Irenaeus fought for its inclusion, but trusted the Holy Spirit had directed the church to the correct conclusion of what books should be included.
Here's some additional discussion on Enoch (Dr. Heiser is a rock solid old testament scholar)
https://vimeo.com/258158162
That doesn't mean the book of Enoch isn't important. It very much is. Especially because, as you point out, the writers of the New Testament read it and even quoted it.
It is not included in the Bible we have today, but there's a good reason for that. It was completely unknown prior to the KJV Bible and all of the pre-KJV translations and collections of scripture, so there could be no way for it to have been included in the Bible we have today. They did not have a copy of it to include in the compilation of the Bible, even though it is quoted and mentioned many times, so it was impossible to include it at that time. However, when they created the Canon of Scriptures, one of the criteria they used for inclusion in the canon was; Is it mentioned and/or quoted elsewhere in scripture? Enoch meets this criteria.
https://bibleprophecyandtruth.com/notes/Enoch
The book of Enoch was well known and very much discussed for inclusion. Irenaeus fought for its inclusion, but trusted the Holy Spirit had directed the church to the correct conclusion of what books should be included.
Here's some additional discussion on Enoch (Dr. Heiser is a rock solid old testament scholar) https://vimeo.com/258158162
That doesn't mean the book of Enoch isn't important. It very much is. Especially because, as you point out, the writers of the New Testament read it and even quoted it.