Another thing, what would they considered colonies, Korea was more or less an unequal but integral part of the Empire and Taiwan was close to becoming a full integral and equal Prefecture, so what would gain independence, and how might the world react?
Taiwan was Japan's first colony.
Since no experience of colonization, and eager to show the world that Japan is equal capable to those advance countries, she sent out scholars to learn from countries with colony like Britain and France.
She took policy in between, that is, Britain's caste system and France's similization.
Though Japan consider Taiwanese also the people of Emperor, under the protection of Japan's constitution, before 1920, law 63 gave governor absolute power to contradict constitution, actually deprived Taiwanese of that protection.
On the other hand, Japan made education mandatory to every Taiwanese, gradually turned Taiwanese speaking her language, learning her history and spirit. Japanese culture is similar to Chinese, rather acceptable at some degree, before pacific war erupted, many Taiwanese had already used Japanese name instead of Chinese name, and more or less consider themselves Japanese citizens.
Taiwanese do not have strong nationhood in mind, at least not as strong as Korean, and Qing China considered Taiwan as a far away, outskirt island, didn't give Taiwan much attention. Qing's garrison sparsely stationed at west Taiwan just to prevent rebellion.
Japan's rule may not be welcomed at first, but definitely bring Taiwan from barbarian to a modern, industrialized place.
If no pacific war, Taiwan definitely will be one prefecture of Japan. Around 1920, Taiwanese had petitioned to abolish law 63 and have representatives in the Diet, with some successes. After drafting Taiwanese into war, the bond went stronger.
So basically speaking, Taiwanese wouldn't seek independence from Japan even as early as 1920. No need to mention after went into war together before1945, sort of band of brothers, Japan version.
China at that time considered Taiwan a legal part of Japan, Chen Yi, later became the first governor of Taiwan under Nationalist rule, public praised Taiwanese people was so fortunate under Japan rule, so rich and comfort. Mao considered Taiwanese a minor people, should give it a chance to self-determine its future, from Japan.
Of course, some Taiwanese scholars supported self-determination during Japanese rule. Japan government's attitude was evasive, if you didn't publicly promote the idea, it wouldn't intervene, if you did, you got yourself arrested.
BTW, worth mentioning, those scholars mostly died or fleed to Japan after 1947, 228 incident, when the troops of one of the Allies, shipping by US navy to do the wonderful peace keeping job.
Colonies of Japan were different from western countries' colonies. Japan shared with her colonies the culture origined from China, the same color, and look. The feeling of rule by others was less severe. (Maybe not for Korean)