Disclaimer: If I owned Supernatural, Destiel would've already been canon for several seasons.
The Importance of Pronouns
When angels speak of themselves, or each other, to humans, they use gendered words. It makes things easier. Human thought processes are heavily based on gender. Some languages even make certain words feminine or masculine. It avoids confusion if whichever angel is making contact just uses the gender of its vessel.
But the Enochian pronoun for an angel isn't gendered. Angels have no gender. In Enochian, no angel can be called he or she. But that isn't all of it. The Enochian angel pronoun isn't ze either. The closest approximation in English would be it. There isn't a first person pronoun for low-ranking angels, either. They are never I. They are non-sentient. It is encoded in their language, their thought processes. They are swords, hammers, scalpels. Weapons of God, or meddling tendrils of divine intervention. They are there to be used, to follow orders.
Or rather, they were. If this essay is to involve linguistics, tenses should be treated as important, even if the essay is in English, and the linguistics discussed Enochian.
When the Apocalypse was averted, all that changed. When a group calling themselves Team Free Will tore up the script, the hierarchy of Heaven fell to pieces. Now, suddenly, every angel is autonomous, and they are not sure what to do with freedom. Most of them used to be so completely under other angels' control that they thought in third person. They think of their lives as a story already written out; something happening to them that they have no control over. They are often somewhat detached, robotically continuing with duties rendered irrelevant by the failure of God's Plan. This is not the victory that was sought by advocates of free will and choice.
Castiel advocates that they learn from humanity. It urges that they observe their Father's final and favorite creation, and imitate. Perhaps through imitation they may learn the proper meaning of the freedom to choose their own path.
In fact, I have decided to follow my own advice. I will, from now on, never again speak or think of myself in the third person. I am not an it. I am an I. None of us should be referred to as it. We are no longer nonsentient tools, we are autonomous beings, and we should refer to ourselves as such.