Is it fair to say that the "enfleshment" of John 1:14 was caused by the Word?
No, it is not.
The word is simply the will, expression, power and outreach of God in His oral decree. The same author John, expressly shows the word as a 'which' or a 'what' and not a person who was 'with' God in the beginning. John recasts the essential core of God's interaction with creation (His word) bywith creation by enlarging and reinforcing the simple introduction in his Gospel.
That which was from the beginning, which we have heard, which we have seen with our own eyes, which we have gazed upon and touched with our own hands—this is the Word of life. 2And this is the life that was revealed; we have seen it and testified to it, and we proclaim to you the eternal life that was with the Father and was revealed to us. 1John 1:1-2
- How is this (it) 'word of life' revealed? In Jesus and in relationship with him.v3
- What have they gazed upon and touched? The word which is now Jesus.
- When did he become the word? When conceived (and finally born) in Mary.
- "And the word was made flesh, and dwelt among us". Only in Jesus is dwelt among us possible.
- Now, Jesus and God dwell within us by the spirit. John 14:23
If John meant 'whom' he would have said so. But no, the 'whom' is Jesus who is that human expression of God's will and intention. He is the one they can now touch and see because he is the word of God embodied. Certainly, the nature of the 'word' or 'logos' is totally representative of God in every respect - what God says will be, will be. This representation is now the human Jesus who also is the source of life, power and decree, being given this authority within God's sovereignty.
The 'word', like Jesus when he was on earth until his resurrection to immortal life, is incapable of doing anything of itself/himself.
John introduces the 'word', the other Gospels explain how it was made flesh through the divine intersection of God with Mary to cause her to conceive a holy child.
The idea of devising doctrine and person on some perceived nuance of Greek grammar, when the text is quite explicit (and supported by itself in other passages), is unsound practise for those seeking the intended meaning of the words God provided.