> Unicode really should have had a similar “no original designs” rule.

I think it does, doesn't it?

Here is some info on unicode rules for new characters, although there doesn't seem to be a single succinct statement, and there are slightly different standards for different categories ("letters" vs symbols vs emojis). But I am pretty sure you can't just make up a character and succesfully submit it to unicode on the argument that it would be useful, this thing you just made up; it has to have already established use to get into unicode, generally.

http://www.unicode.org/pending/proposals.html

Which characters are you annoyed by specifically?

It's true there are separate rules for emoji's, which are... weird. I seem to recall unicode initially tried to resist emoji's at least to some extent, before just giving in.

But emoji's are actually pretty clear, to me, as a success of unicode. People want them, they have achieved pretty widespread use globally, and if that's going to be so, we benefit from them being encoded in a standard vendor-neutral way. We're far better off with emoji's in unicode than, say, every vendor using their own non-standard use of private codepoints. (Unless you argue that if they weren't in unicode they wouldn't have caught on; I am sympathetic to the argument that we'd better off without emoji's, but I'm pretty sure if they weren't in unicode we'd still have them, just non-standardly).

Here are some of the guidelines for which emoji's will be encoded in unicode:

https://unicode.org/emoji/proposals.html#selection_factors

It's a bit fuzzy, but you generally can't simply get a new thing you just invented encoded in unicode on the argument that it's cool.