Why wasn't the Logos included in the Nicene Creed?

Emperor Constantine I and the bishops of the Council of Nicaea (325)

holding the Niceno–Constantinopolitan Creed of 381 (sic!)

When the First Ecumenical Council was summoned by Emperor Constantine I at Nicea, in 325 CE, Eusebius of Caesarea came with his local Creed, convinced that it would be accepted, or anyway used as a basis for general Creed of the Catholic Church. Here it is:

“We believe in One God, the Father Almighty, the Maker of all things visible and invisible. And in One Lord Jesus Christ, the Word of God [ho logos tou theou], God from God, Light from Light, Life from Life, Son Only-begotten, first-born of every creature, before all the ages, begotten from the Father, by Whom also all things were made; Who for our salvation was made flesh, and lived among men, and suffered, and rose again the third day, and ascended to the Father, and will come again in glory to judge the quick and dead. And we believe also in One Holy Ghost” (Eusebius of Caesarea, Letter on the Council of Nicaea, @ Catholic Encyclopedia – emphasis added)

In the second article of this Creed, it is declared that the "One Lord Jesus Christ" is the "Word of God" (ho logos tou theou).

If that phrase had been adopted in the Nicene Creed (without any pre-existent personal overtone, but simply stating that ho logos tou theou, in accordance with John 1:14, sarx egeneto – the logos being an essential attribute of the One and Only God), it would have clarified the Catholic doctrine on this essential point. 

Then why wasn’t it included in the Nicene Creed?

Certainly not because the expression isn’t scriptural: in fact it reflects the very contents of the Prologue to the Gospel of John (John 1:1-18). More, unlike homoousios, which is definitely not scriptural, and in fact was even first used by the Gnostics ("before the Gnostics there is no trace at all of its existence" – see von Harnack, Ortiz de Urbina, Mendizabal, Prestige, Gerlitz, Boularand, Kelly, Dinsen, Stead), and was even condemned in at least one of the Synods of Antioch (264 – 269 CE), held against Paul of Samosata.

So why wasn’t it adopted? Perhaps the possible explanation is that what turned out to be the Symbol of the Apostles, in its earliest version (vetus symbolum romanum), was so ancient, that, in fact, it was (probably in its Greek or even Aramaic text) of truly Apostolic origin, so ancient  that it did not incorporate the doctrine expressed in the Prologue to the Gospel of John, which Gospel, for quite some time, was not even included in the Canon.

Here is my hypothesis.

While the Conciliar Fathers at Nicea had no qualm with adopting the un-scriptural, even originally Gnostic homoousios, so as to quash the Arians, they were reluctant to incorporate the fully scriptural logos tou theou, because it was not part of the earliest Apostolic Symbol.

In much later times, Augustine of Hippo showed how much sacred respect there still was for the intangibility of the Symbol of the Apostles. Augustine, who spent many pages on the Symbol of the Apostles (in particular his Sermons from 212 to 218 - although he does not explicitly call it "of the Apostles"), solemnly states, addressing the catechumens:

"You should not write it out in any way, but, so as to hold the exact words of the Creed, learn it by listening. Not even when you have learned it should you write it down, but, rather, always hold it and cherish it in your memory." (Sermon 212 On the Presentation of the Creed, Saint Augustine, Sermons On The Liturgical Seasons, translated by Sister Mary Sarah Muldowney, in The Fathers Of The Church. A New Translation. Volume 38 [<= link to PDF file], p. 120 [144/486])

It is evident from his Sermons that the Symbol to which Augustine makes reference is essentially the same as the vetus symbolum romanum. Unlike Rufinus, who motivates the prohibition to write down the Symbol with the risk that it may end up in hostile hands, Augustine does not motivate his prohibition to put the Symbol in writing. By Augustine’s time, the necessity, dictated by the clandestinity of the early Christian Church, to consider it as a "secret watchword", was superseded. But it is highly significant that the traditional ban was strictly retained.

In recent times, reading a seasoned Journal Article, "The Earliest Text of the Old Roman Symbol: A Debate with Hans Lietzmann and J. N. D. Kelly" (D. Larrimore Holland, Church History, Vol. 34, No. 3, Sep. 1965, pp. 262-281), made me realize the full extent to which those highly respected scholars went so as not to admit the most probable explanation of the close similarity between H and R, viz. that the vetus symbolum romanum was the prototype from which all other regional variants, and all baptismal creeds were derived.