You have posed a good question and I am happy you've done so.
The question itself is at fault, as it assumes incorrectly what the
Holy Christian Church teaches with regard to prayer.
First dear brother, you should know the purpose of prayer. It is
nourishment for our souls, just as food is for our bodies. Prayer is
a necessity of life, a practice in which we all must engage to attend
to our spiritual well-being.
That said, I want you to now consider where written prayers come from.
They don't begin on paper, they begin in the hearts of those inspired
by the Holy Spirit. For example, much of our Holy Qurbono is written
by the same hand who authored a New Testament epistle (St. James).
Other portions are directly from the Scriptures themselves, and still
more are composed by these holy men (such as St. Ephraim, St. Jacob of
Serug), whose hearts yielded to the Holy Spirit so much, that their
praises to God shine of righteousness until this day.
Let us also remember, that Christ, when He taught us to pray, taught
us "Our Father, who art in heaven..." and not, "think of me like a
good friend and just say whatever is on your mind."
Beyond the Holy Qurbono, the ShHimo, the Beth Gazo, you will find in
the writings of our fathers and mothers, their own prayers from the
heart. So now we should ask, does the Church really teach that prayer
from the heart should not be practiced?
Quite the contrary! Prayer of the heart is the beginning of all
vocalized and written prayer. In fact, the more you become acquainted
with the holy fathers and mothers of our Syriac Orthodox Orient, the
more you will find that this is indeed the main point of their teachings!
The holy prayers that have come down to us from the beginning of time
encompass anything we may deal with in life. First, let us pray the
prayer of our hearts, keeping them in the quietness of our own souls.
Then when we have submitted to God from within, and we are prepared
to open our mouths, let us pray the canonical prayers, which feed our
souls and strengthen our spirits. Then, however your heart dictates,
be it praise, thanksgiving, or sorrowful petition, open the chamber
door of your heart and let these feelings pour fourth as needed.
I'd like to recommend a few books to you:
The Spiritual Treasure on Canonical Prayer, by H.H. Ephrem Barsoum
The Syriac Fathers on Prayer and the Spiritual Life, by Sebastian Brock
If you send me a personal email, I can help you get some of these or
recommend some other books to you.
Pray for us,
St. Mary's and St. Ephraim's