I would very much like to see tear-themed items. A single dramatic tear, smudged mascara/eyeliner, waterfalls across both cheeks...there's no way to get this from CWs, except for that one super-expensive item, and I think it could be incredibly interesting.

Also another eyebrow feature, furrows where the brows form a ridge over the nose and angling into the forehead. It could be anything from furious anger to gleeful evil depending on the mouth and just in general could be shorthand for a lot of different stories.

I really like this, it'd add more depth than just eye and mouth shape.

For the sad items, it could be a set of tissue-related items (Tear Stained Handkerchief, Makeup Stained Handkerchief, Soggy Handkerchief) put in Grooming Parlor maybe? Basing that on the recent sets to go in there.

That was my thought. And for the brow furrowing with anger and so forth, definitely have something in the description about your face freezing that way. :)

I thought of another eye item, too; tears spraying out of the corners of the eyes, for comedic effects or so-happy-they're-crying HAs.

I'd also like to see surprised, shocked, annoyed, irritated, fearful, infuriated and elated! XD

I support more emotions like that, I love the ideas in the OP

I wouldn't mind adding some personality to my HA through facial features. These might be wearables that even I'd actually consider using :)