I can't think of one. There are already far too many of them to view at once on a phone, so adding more doesn't make things much more disorganized. Storage capabilities also grow faster than the standard adds new symbols.
Frankly I think it's a bad look when people suddenly become very passionate about opposing updates once they are reminded of the existence of dark skinned emojis. They're just silly little drawings, people. If someone is so upset by others being able to send silly little drawings that vaguely resemble themselves, they should do some introspecting.
Time used to implement all of these things is time not spent working on more 'useful' things. Like, from a comment up-thread, languages and scripts that people use in their daily lives:
Frankly I think it's a bad look when people suddenly become very passionate about opposing updates once they are reminded of the existence of dark skinned emojis. They're just silly little drawings, people. If someone is so upset by others being able to send silly little drawings that vaguely resemble themselves, they should do some introspecting.