One thing that irks me a ton with fonts I otherwise like is when characters/sequences like "~". ":3" and "<3" don't look good in text... I might not be a VN creator, but I still write a lot of dialogue in my games, and being robbed of an easy way to put emotes is a pretty nasty surprise. Having special heart characters, symmetrical 3s that look great in smileys, long curly tildes, perhaps even the small omega or a curlier w for OwO and its ilk... you get my drift, providing nice characters that can be used for smileys and verticons would be a big plus in my book~
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That sounds cool too! I guess with individual glyphs you have more freedom to try out unique combinations the font maker might not have thought of (that's how the traditional smiley was born, after all :P) but there's probably a bigger potential to make professional-looking symbols if they're handmade because you can make sure they look good. Decisions, decisions... actually, you could always include the radicals used to build the dingbats as separate characters to bump up the character count without additional effort :P (Assuming you make stuff like "=w=" which makes sense to break up like that, of course)