Rooftops and shots of the sky are a motif I've picked up on in TG. Like when a character will be espousing their worldview it'll be juxtaposed with a picture of the sky or they'll be talking on a rooftop. Ex: Kaneki and Amon's conversation, Amon's speech to Akira about living with emptiness, Kaneki telling Hide he wants to take responsibility. Is there a deeper meaning to these shots other than a cool aesthetic?

I see them as a way of framing a character next to the wider world. As you say, they’re usually discussing their world view - the sky shows how this single figure has adapted to survive in a world which wears them down. Shots of the sky (along with the moon, earth or rays of the sun) often accompany statements on the world’s nature.

Night skies often accompany negative moods, while brighter skies tend to demonstrate hope or new direction, as with the examples you listed. I always felt the rising sun in the last chapter of the first series gave it a tone of biting irony, that day is here but everything the sun now shines upon is tragic. But the last page shows how the brighter sky is a subtle indicator of hope for the next series.

And then, when we get there…

What we enter is not immediately a tragedy, but rather a series where our protagonist is, though not fully, far happier than we’ve seen him before. As the yellow text says, the sky next to the tragedy is a clear blue, and I believe this applies to the story of :re as a whole. 

The original series has many moments at night-time, whereas :re tends to have more blue skies as hope is gradually rising. The exceptions to this rule are when tragedy returns to :re when Kaneki regains his memories and continues his tragic story:

Kaneki’s talk with Takizawa, where both are shown to essentially be hanging onto a thread to stay alive.

The talk between Uta and Donato on the rooftop, with the Clowns being the most nihilistic characters of the series…

And the rampage of Dragon, perhaps Kaneki’s darkest moment of all, which is also preceded by this artwork as the attack on the 24th Ward becomes well underway. The darkness and “shadow” is telling, as is the chapter title: Night Comes. This is also the chapter where the strength of Roma, a Clown (therefore associated with night), is demonstrated.

But still far moreso than the original we see lighter skies focused on in :re. Even if the skies and circumstances are cloudy, light still escapes them. I’m holding out for a sky of the most brilliant blue yet to be the ending shot to perfectly wrap up this series. The light shone on the world in 176 is the most hopeful image we’ve had yet.

You’ll have noticed that a lot of these images also incorporate shots of the city as well. This is also about placing actions within the wider context of society, and that city we often see in the background is brought dramatically to the fore with Dragon, where Kaneki’s actions completely change the landscape. 

The sky and the city both function as a way of showing the interaction between the world and the individual, and this latest tarot, The World, has introduced a harmony where the world is no longer ‘wrong’ for the individual or at odds with them, and has demonstrated the value of responsibility and selfless dedication to the wider, city-saving, world-saving goal.