One of the major goals of Unicode was to support round trip conversion from all the widely-used character sets into Unicode, and then back out again. In particular, supporting popular Japanese character sets was important for technical and commercial reasons.

There was a lot of weird stuff in the world's character sets.

Emoji were first used by Japanese cell phone carriers. They were encoded as Shift JIS characters, but in incompatible ways. The Unicode Consortium had no real interest in this until Google and Apple basically said, "If we're going to have to support all these character sets, could we please standardize them?"

I think it's just the reality of standardizing the world's character sets. A lot of weird legacy stuff will slip in, and other countries will want to standardize things that seem unnecessary. Personally, I'm very thankful that somebody wants to do all the exhausting political work of coming to a consensus. A few snowmen are small price to pay.

Playing card symbols are -- like chess symbols -- typeset inline with ordinary text in books that deal with the strategy of those games. So, IMO it makes since to include them in a character set that a font and typesetting engine will support.

Well right now it's about two percent of unicode, right?

And people use them as text, so there's a reason to add them and not much reason to refuse them.

You might be right, but where are you getting the 2% from? Are you thinking of just emoticons, emojis, playing card symbols, and snowmen? There's more than that I'd question.

I looked up how many emoji there were, added some for wingdings, and rounded up a bit.

What else would you question? Would it be more than 1500 more, which would bump it from 2 to 3 percent?