It has nothing to do with that. Taiwain is in all practical things a self governed state protected by a superpower and the status quo. They don't need to formally declare independence. It will cause nothing but problems for them.
China will see a decleration of independence as an end to any hope of reunification, nationalists will be in incensed and Xi will face immense domestic pressure to invade. The US is likely to consider the decleration unwise and a break with the status quo, causing them to limit their involvement to supplying Taiwan. The reason for that will be the other S.Asian countries. Because they will primarily be worried about Chinese agression and a change to China's relatively stable foreign policy.
If China attacks without any change to the status quo, that would likely be considered a substantial change in China's regional strategy and one that would spark a fuse under the powder keg among S.Asian countries. Japan would militarize, S.Korea would worry US has lost control, N.Korea would take advantage and join China, Russia would provide ample unofficial support to have the US distracted and suddenly the entire region would be an unstable mess. The US would have no choice but to enter the war as an active participant because of their active guarantees or watch as the world is engulfed in chaos because it would signal to the world that the US no longer has the influence or power to maintain world stability. Japan will be wanting nukes and Korea will explode, US influence in the region evaporates and the world's supply of technogy dries out. If China moves first, it's world war three.
That likely won't happen if Taiwan is the one to change the status quo. At that point it's not a change in Chinese regional strategy or agression. Other S.Asian countries will be less concerned and partly view it as a self-inflicted situation given that Taiwan went against the status quo they all rely on for stability, and look for the US to ensure the conflict is isolated to Taiwan and not brought to their door step. They will push for ambiguity about US protection of Taiwan, and they will get it. It's a different dynamic all together. They will be concerned that the radical shift in Taiwan's politics will drag them into a war through the US. The US will increase military presence in S.Korea and Japan to prevent a massive increase in militarization, while assuring them that they will stand against Chinese agression should the chinese look beyond Taiwan. Everyone will pay lip service to Tawian's right to independence while quietly hoping Taiwan manages to wound China a bit and China can appease the domestic crowd by taking Taiwan. When that war ends, they will all reasses the situation and likely land on a new status quo.
So I ask you, what is the point? Why do it? It's not a question of morality.