I find introducing "new" unicode glyphs for characters that have historically been in wide use is extremely useful, as people working with historical texts no longer need to use workarounds to express them. See [1] for an example of the kind of characters you find in historical texts. Having an official way of representing anything that's actually (or has been) in use makes sense. Whether that's the same as recommending it for widespread adoption is a different question. Several German-speaking countries have dropped the ß from their orthography, but still agree on what the ß character should look like and how to represent it in text.

Now, emoji, OTOH, just feels to me like unnecessarily polluting the character space. I'd much rather have a capital ß in the codespace than some smiling poo family.

[1] http://www.unicode.org/L2/L2015/15327r-n4704-medieval-punct....