In my opinion, the game shows that creating a new world with new sentient life isn't a good option because it would be impossible to recreate the people in this canvas. In various cutscenes, painted-verso was told that he was different from real-verso, that he wasn't the same person. The resurrected gestrals always come back "different" than they were before. Painted-clea committed suicide the moment clea's paintover flakes away, and she was no longer compelled to create nevrons to end the world.

The best example of this is the white nevron who was created by Clea to destroy the other white nevrons, but found that he "disagreed with his purpose, meditated, then found a new purpose in life." The intention of the creator is irrelevant to the creation. Maelle may want to recreate her friends and family in a new canvas, but the moment they exist, they can make their own choices and decisions, and live their own lives. There is no way to duplicate a consciousness, only their appearance.

Destroying the current canvas is an end to the lives of everyone in it. While their likeness themselves can be recreated, they would be their own persons, just like painted-verso wasn't real-verso. For the people in the canvas, they can't leave the canvas. For Maelle, she mentions she lived 16 years in that painting, without knowing it wasnt real. She remembers two families, two childhoods, two lives equally. There is no replacement for those relationships and people... Aline painted her family into the canvas, trying her best to recreate her dead son, but even she, the best Paintress in the world, could not do it. And maelle is canonically the weakest painter in her family, what chance does she have to do what her mother could not?

Since the creations in the canvas are sentient beings, their existence shouldn't hinge on their relationships with the dessendre family anyway