I think each Goku transformation has their own unique narrative importance outside of SSB and SSJ2.
The Oozaru is the beast and monster that needs to be contained by Martial Arts, the very essence of what it’s discipline seeks to tame.
Super Saiyan is the awakening of Legend, a righteous heart fueled by fury that could only be achieved by being everything a Saiyan simply isn’t.
Super Saiyan 3 is the essence of the Otherworld made into a form, and specifically is a failure because it is meant to be a subversion of the “new form = wins,” trope Dragon Ball was getting into.
Super Saiyan God is, in my opinion, a perfect transformation. Narratively speaking, Goku is ascending not towards the Gods not because of his “unga bunga strength” or “big mad,” but because of his GOOD DEEDS. This theme is very prominent in Dragon Ball and is acknowledged twice—Once at the 23rd Tenkaichi Budokai and yet again at the Tournament of Power. The opportunity to turn into a Super Saiyan God came not from strength, but from Goku’s ability to see kindness in others and grant them the ability to improve themselves as people, which they then do good on. It’s those people who then give him the power of a God.
Super Saiyan Blue has none of this. It is a form to be a form. The Manga admittedly writes the form far better, but even in said Manga there’s no narrative weight behind it. It’s really just the circumstances they can use the form, efficiency, etc.
However, things AROUND Super Saiyan Blue do have these narrative through lines.
Goku only gets the Super Saiyan Blue Kaioken by tapping into the power given to him by a friend—Which he specifically met from his own good will, as that is what got him the opportunity to train in Otherworld with his physical body.
Vegeta gets Super Saiyan Blue Evolution from his tapping into the good will (promises/dreams) of Saiyans from another Universe. His Student, who he lost. It’s made explicitly clear that, narratively, this form is the reward for not only having changed, but seeking to grant that change to other Saiyans. You can even add in his insecurity over the Saiyan race into this, as Zamasu steals the embodiment of the changes Saiyan (Goku) and perverts it—Hell, he becomes a better “Saiyan” than Goku or Vegeta were with it, and you can reason this shook his beliefs. Which in itself can be supported with the Bulma scene—Vegeta realizing that not even his wife views him as a solution to the problems, and instead relies on Goku.
In the Manga, there’s the additional Perfected Super Saiyan Blue, which is narratively supposed to be the apex of what the form is—A release of the constraints of the transformation and fully embracing Godhood, or really what it MEANS to be a God. Hence why the form debuts against a Fallen God, and why 90% of the imagery Goku and Zamasu have in relation to each other is the enlightened and unenlightened respectively.
Ultra Instinct really is just more enlightenment stuff. If anything, while narratively it is earned, correctly built up to, etc. it is just what SSG was MEANT to be before they rushed into a new form in RoF.
