> Why does Unicode specifically need to include novel "innovations"?
Unicode chose to get into emoji because Japanese carriers were already making their own private character sets with emoji, and Unicode has a goal of being a superset of all other (relevant) character sets. (Arguably emoji support in Unicode has been a resounding success. Look at the world-wide enthusiasm around each new Unicode version that gets announced now!)
It also brought broken handling of code points beyond the BMP to the forefront and dealing with Unicode text is correct in much more places by now. Previously the only people who noticed were those who needed obscure Han ideagraphs, hieroglyphs, and other things that are not terribly useful or interesting to the vast majority of people.
Unicode chose to get into emoji because Japanese carriers were already making their own private character sets with emoji, and Unicode has a goal of being a superset of all other (relevant) character sets. (Arguably emoji support in Unicode has been a resounding success. Look at the world-wide enthusiasm around each new Unicode version that gets announced now!)