On the positive side I should make a few comments:
1. It seems as though a prophecy from Enoch was preserved by Jewish tradition which was cited by the Scriptures as the 7th man from Adam. It also seems apparent that some late BC Jewish writer/writers developed a book/books around some of the preserved prophecies of Enoch so that is is impossible now to determine which parts may have been original with Enoch and which parts are interpolations. However the author was recognized as Jewish by both Jews and the early Christians.

2. The book of Enoch, along with many other of the Greek Apocryphal books were a great source of Jewish history in the ancient world. The Jews were scattered in diaspora and these books were cherished as testimonies of their people who still lived in Palestine. Therefore some of these Books the Jews appended to their Septuagint translations of the OT.

3. Since these books were written by Jewish authors and they interpreted OT prophetic Scriptures in a way that anticipated the NT record, they were of great value to the early Christians as apologetic tools. For example the Septuagint said that Messiah would be born of a virgin illustrating His deity and the Book of Enoch says,

There I beheld the Ancient of days, whose head was like white wool, and with him another, whose countenance resembled that of man. His countenance was full of grace, like that of one of the holy angels. Then I inquired of one of the angels, who went with me, and who showed me every secret thing, concerning this Son of man; who he was; whence he was; and why he accompanied the Ancient of days.

When they could quote Jewish writings to unbelieving Jews and show how their OT scriptures and other writings correctly identify Christ as deity--this leaves the Jews in a very awkward position to defend their unbelief. They had to invent new interpretations of OT passages in order to justify their rejection of the deity and Messianic role of Christ.

These were some of the reasons why "some" early Church leaders thought these books should be included in the canon. In the end the Church discerned what Christ had already revealed in His Gospel teachings, that the canon was already defined by the Tanakh. The Church merely agreed with Christ in this discernment. The extent of the NT Scriptures was never in any serious question.