As a matter of fact, they were a part of the KJV for 274 years, until being removed in 1885 A.D. Also, they were part of the Jewish Tanakh, The Old Testament, during the time of Y'shua, Jesus, but disappeared from the Jewish Bible, the Masoretic Text, between the 7th and 10th century AD. If you research it, you'll find that not only did Y'shua and his disciples quote it, so did the early church. So, why did it disappear from the Masoretic Text and eventually the Christian Bible?
Well, the reason, for Apocryphal Books not being in the Masoretic Text, is that a very influential group of Jewish scribes took it on the themselves, to remove a lot of Messianic references, from the scriptures. This was in response to the ever-growing movement of Christian on Jew violence and Jews accepting Y'shua, Jesus, as the true Messiah.
Let us lie in wait for the righteous man,
because he is inconvenient to us and opposes our actions;
he reproaches us for sins against the law,
and accuses us of sins against our training.
He professes to have knowledge of God,
and calls himself the Son of God.
He became to us a reproof of our thoughts;
the very sight of him is a burden to us,
because his manner of life is unlike that of others,
and his ways are strange.
We are considered by him as something base,
and he avoids our ways as unclean;
he calls the last end of the righteous happy,
and boasts that God is his father.
Let us see if his words are true,
and let us test what will happen at the end of his life;
for if the righteous man is God’s son, he will help him,
and will deliver him from the hand of his adversaries.
Let us test him with insult and torture,
that we may find out how gentle he is,
and make trial of his forbearance.
Let us condemn him to a shameful death,
for, according to what he says, he will be protected.