Let's not forget that adding all this complexity to Unicode has a real burden for people who implement Unicode. In practice, the consortium has to prioritize what symbols to support. So, in practice, it's less "embracing all variants of human expression", and more "the ability to communicate in your native language doesn't matter as much as the gender identity of this police emoji".
And while you’re correct that emojii do require some amount of UTC resources, it’s worth noting that most of that work is done by a special subcommittee to not distract from the mainline work of other languages, and that emojii have brought new attention and new volunteers to TUC - so I’m not sure how significant the impact of adding emojii to their workload really is.
I would summarize the key issues here, but they are complex and I don’t feel qualified to do them justice.
In any case, please see the comments on the HN post (linked by a sibling comment) for that. The issue is in fact wickedly complex, and it’s not clear (even among Bengali speakers) that this is a deficiency in Unicode (vs a deficiency in text entry and rendering software).
We're talking about emoji for crying out loud, the entire idea is frivolous (and that's fine!)
For example, the US flag is composed(?) as U+1F1FA U+1F1F8 (REGIONAL INDICATOR SYMBOL LETTER U) and U+1F1F8 (REGIONAL INDICATOR SYMBOL LETTER S).
It can get even crazier with “emoji tags”[1]. Say you want to encode the flag for California, US. You’d think it’d be done using those regional indicators as “CA”, but that’s actually Canada. The way to do it is: U+1F3F4 U+E0075 U+E0073 U+E0063 U+E0061 U+E007F. This encodes a black emoji flag, “USCa” in tag characters, and a “tag cancel” code point.
Basically, if your font has symbols for countries that don’t exist yet, or are missing some, that’s on the font designer, not Unicode.
[0]: https://en.wikipedia.org/wiki/Regional_indicator_symbol
So all that to say: Unicode is still representing language and/or written culture as it is at a point in time (which may be less relevant in the future) - and that’s OK, and absolutely compatible with their aims.
Unicode describes flags of nations that no longer exist, dead languages, etc - I don’t see why having a few pictograms that may or may not be relevant in 1000 years time is the place to draw the line. If skin tones play a role in pictographic communication today, then that’s good enough for inclusion.
Put another way: Unicode seeks to describe all human written language. Emojii is unusual in that TUC is actively playing a role in the evolution of the language, but they’re still trying to describe a written language the way people want to use it. This feature sees a lot of use, which to me says that TUC has correctly described how people want to use pictographic communication.