Yes, but they have alternate italic forms, for example. Sure, some one of the glyphs like с doesn't have an alternate italic form. Since the other ones do, it would be weird to only assign a separate codepoint to some of them and overlap the others. It would be a workable solution, but still weird.
Which is a bad idea because the characters don't look right unless you use a Japanese font. But if you want to write an article comparing Japanese and Chinese characters, you have to use two different fonts.
