This is a point that has often been made, but is always worth remembering.
Nicaea was not the fullest formulation of the doctrine of the Trinity.
The Bible itself, especially in Moses, gives the richest, fullest and deepest doctrine of the Trinity - with the greatest range of titles and imagery.
In the Creed we get a mere snapshot of a few Biblical truths about the Trinity.
The post-Nicene Church is not in the slightest bit "more Trinitarian" than the pre-Nicene Church - or "more Trinitarian" than the ancient Church of Abraham, Hagar, Moses and David.
The Nicene Creed was formulated in order to reject a NEW doctrine of God invented recently by the neo-Platonist Arius - in which God the Son was a mere divine creature and God had undergone a radical change (of name or nature) at some point in time prior to the creation of the universe.
This crazy NEW doctrine of God was resisted with the most ancient doctrine of God - the doctrine of God found in Moses and the prophets.
Read carefully how the Nicene Church leaders resisted the philosophical sophistry of the Arian philosophers - in the eye-witness reports and the Council minutes, spread over that interesting month in 325 AD.
[Perhaps start with this brief account from Gelasius - https://www.fourthcentury.com/gelasius-of-caesarea-ecclesiastical-history/
and then luxuriate in these three volumes of glory! - https://www.fourthcentury.com/anonymous-church-history-cpg-6034/ ]
The Nicene Church leaders turn to the Bible to express their unchanging, ancient faith - and in many ways see the whole debate as a fight between the ancient Bible and the new philosophers.
As Gelasius says - "Present at the synod were philosophers extremely well-versed in dialectic. Among them was one who was wondered at by all and who sparred with the bishops very often on Arius’ behalf..."
Furthermore, the Church leaders at Nicaea were reluctant to introduce any language that is alien to the strict language of the Bible.
The word "homoousios" seemed a very unsuitable word because it had been used by heretics to promote modalism - especially the modalism of Paul of Samasota.
To describe the Father and Son as "homoousios" had previously seemed to suggest that they were exactly the same person - the very same identity - as modalists had done. Or that the Son was a fragment broken off from the Father - making the Son into one who had not always existed.
In addition, the gnostics used the word "homoousios" to say that all the divine aeons (created divinities) all shared the same divine substance - they were all "homoousios".
So a word with such heretical and gnostic ancestry seemed to be out of the question!
However, although the word had been rejected as heretical by the Council of Antioch (264-269), Constantine liked "homoousios" because it seemed to get right to the heart of the issue in the context of the anti-Arian arguments of the council... and if Constantine liked it, even the many hesitations of Eusebius of Caeserea could be overcome!
If the Arians refused to confess that the Father and the Son were of the same being (homoousios)... then even an unpromising word like that might be dusted off and repurposed to express Biblical truth.
Yes, there was nervousness about this... but the more strictly Biblical Church leaders were reassured that that this was not intended to be a departure from the Bible but an expression of the Bible.
The key thing to note is that there is no new doctrine of God at Nicaea. Far from it!
The entire reason for the Council of Nicaea was to reject, resist and actually condemn the NEW doctrine being infiltrated by Arius - powered by the infestation of neo-platonism into parts of Mediterranean Christianity.
The Council of Nicaea was a global, biblical Church council acting as doctrinal white blood cells - converging on the infiltration of neo-platonism, blocking it and trying to reject it once and for all.
[Sadly, this was not the last they would see of the neo-platonist parasite.... but that is a much longer tale!]