I suspect this is caused by a variety of factors.
1. Even APPLE likes to focus on them. As you said, they are 'such a small' thing that I can't quite fathom why it's such a big deal. Implement them... don't spend your time talking to technical people about them.
2. We are collectively already overburdened with emoji's. Sure... they're cute. Even some of the sets I can buy are great. But at the end of the day there are only so many you can use on a regular basis. Probably less than 100.
3. Given #2, the fact that Apple is adding 10... 100... or even 1000 more emoji's is not of value to most people.
From my perspective it's a total "who cares", but I can see them being used to drive updates.