Disclaimer: I own nothing of Dragon Flyz, which is owned by Gaumont Pictures. Only the plot is mine.
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Daybreak on Old Earth wasn't very special.
With the thick clouds of the Warp Winds covering the sky, all the rising sun managed to do was just lighten the area it shone on. It was the reverse for sunsets, where the sky would just darken and so would the land below, except for the lava flows and pools and the various purpose fires lit by the denizens of Old Earth.
To truly see and appreciate the beauty of the rise and set of the sun, one needed to be above the clouds. So the inhabitants of Airlandis had another little luxury that those below didn't, another thing for those below to envy of those above.
Another little reason that Dread Wing wanted the flying city, however small a reason it might be.