Al-Ja'd bin Dirham (ex. 124H) and Jahm bin Safwan (ex. 128) spread the belief of the Qur'an (that we hear, recite and memorize) being created because it opposed the proof of "hudooth ul-ajsaam" that they used against the atheist Philosophers. The Mu'tazilah took up this saying and then Ibn Kullaab (d. 240H) innovated a new saying never heard or spoken of before, "Kalaam Nafsee" with which he intended to reconcile between the saying of the Mu'tazilah, Jahmiyyah and the position of Ahl us-Sunnah. So he said, this Qur'an we have is a "hikaayah" (quotation) and it is created, and the Qur'an that is uncreated is from the eternal "Kalaam Nafsee" (singular meaning with Allaah's Self). Abu al-Hasan al-Ashari, sitting in the circles of these Kullaabis took up this saying and made a minor modification to it saying that the Qur'an we have is an "ibaarah" (expression) of the eternal, uncreated "Kalaam Nafsee" that is with Allaah.

And the underlying purpose in all of that was to avoid affirming for Allaah, that He has actions tied to His will and power, because this would mean, according to the aforementioned intellectual proof based around the basic notions of Aristotle's "Ten Categories" (al-Maqoolaat al-Ashar) that Allaah is subject to change (taghayyur) denoted by His actions tied to His will and power. Because they had already argued against the Atheist Philosophers (through this metaphysical language) that anything having incidental attributes (a'raad) or what they call occurrences (hawaadith), is a proof of its being created, and this is what they used to argue that the universe is created. Then, they had to in turn deal with those texts in the revelation that clearly establish for Allaah actions tied to His will and power (which would have meant that Allaah is subject to occurrences and events and thus created). And because they made this false proof to be the ultimate truth without which the veracity of Islam cannot be established, they had to make this proof decisive, and the revealed texts to be subservient to this proof.

Thus, the central axis and goal of all these people (the Mutakallimoon) to avoid falsifying their intellectual proof called "hudooth ul-ajsaam" (proof of the createdness of the universe) - you can learn more about that here - and this is what drives the bulk of their positions in creed.