Emojis, among other things, are not universally supported, are not consistent across systems, and require additional formatting on the part of the terminal. Having support for UTF is great, but forcing non ascii characters onto users for something as frivolous as emojis is perhaps better avoided.
You can use --quiet to disable non-essential output.
If people are repeatedly requesting to remove a feature, it is, perhaps, symptomatic that that feature should not be your default.
Look, nobody is forcing anything onto users. My read on this situation is that the vast majority of people using Black are okay with the emojis being part of the output by default. My opinion is that terminals incapable of displaying these characters are broken, not the tools that output them. Your opinion might be different, and that's completely fine.
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If people are repeatedly requesting to remove a feature, it is, perhaps, symptomatic that that feature should not be your default.