Quran, like the Torah and the Gospel, is a book with a great message, "WORSHIP GOD ALONE". Thousands of years ago God gave the Jews the Torah in their own language. The Jews then considered the Hebrew/ Aramaic as the special (Holy) language of God. Some of their Rabbis even taught the Jews that praying in any language other than Hebrew is unacceptable to God and that the angels of God do not understand the prayers if not read in Hebrew. Then God gave the followers of Jesus, the Gospel in their own language and they felt the same way that their language, mainly Aramaic is the very special language of God.
Then God gave the world the Quran in the Arabic language. And again history repeats itself and the Arabs thought that Arabic is the language of God. They never appreciated that God gave His previous scriptures in other languages, namely Hebrew and Aramaic. They never appreciated the fact that in all the languages that the scriptures came down with, the most important single fact is that the message has been always the same. "WORSHIP GOD ALONE." They never appreciated the fact that to God belongs all the languages of the world, He created them, just like He created us, See 49:13 and 11:118-119.
Those who can read Arabic can appreciate the excellence of the literature structure of the Quran. Those who do not, can appreciate the excellence of the message by reading the Quran in any language.
God, the Almighty, the Knower, the Cognizant knows that the majority of the Muslims in the world will not be reading , speaking or understanding Arabic. About 80% of the Muslims in this world cannot read, understand or speak Arabic.
SO, WHY AN ARABIC QURAN ?
Only those who understand the purpose of the book will understand why it is in Arabic or non-Arabic.
Quran is a book of a message and not a book of entertainment. God knows that HIS MESSAGE can be and will be translated to all the languages of the world and that the true believer will get His message in any place that was destined to be. God would not send a message that cannot be given to everyone clear and unambiguous. God would not send a message in a language that the people cannot read, speak or understand then punish them for not knowing what His message is.
God clearly told us in the Quran that He does not want any hardship in His religion. God did not put any hardship on these millions (or bilions) of non-Arabs to master the Arabic language before getting His message. See 22:78 Getting the message and enjoying the literature excellence of the Quran are two different matters.
The contemporary Arabs of Muhammed listened to the Quran and appreciated its literature excellence but many of them did not believe then, e.g. Abu Jahl and Abu Lahab, Muhammed's own uncles. Many of the contemporary Arabs of today read the Quran in Arabic but do not appreciate the message of the Quran, they belong to the same group as Abu Jahl and Abu Lahab.
It is the message of the Quran that actually counts, and THANKS GOD, it is the part of the Quran that can be translated. If that message could not be translated, there would not be there these 900 million Muslims who do not know how to read, speak, or understand Arabic.
The inability to appreciate the literature excellence of the Quran is but a minor loss if the message could be appreciated, since the purpose of the excellence in literature was one way to get the people to accept the message. In other words, appreciating the message by a non-Arabic speaking person is like going to the conclusion without passing by all the proofs.
This is in contrast to many of those who had the proof, read Arabic and see the literature excellence of the Quran but failed to uphold the message . Many deceived Arabic speaking people put too much emphasis on their ability to appreciate the literature excellence of the Quran while missing the point of the need to appreciate the message itself, by following it.
Understanding that God guarantees that the MESSAGE of the Quran will be given to the whole world in any language in any place, means to understand that having the Quran as an Arabic or non-Arabic book would not make the difference and that is exactly what God is teaching us in 41:44
[41:44] If we made it a non-Arabic Quran they would have said, "Why did it come down in that language?" Whether it is Arabic or non-Arabic, say, "For those who believe, it is a guide and healing. As for those who disbelieve, they will be deaf and blind to it, as if they are being addressed from faraway."
Also, please read Appendix 4 of the authorized English translation by Rashad Khalifa, Ph.D