joveian: Obviously it takes some skill to do well, and like all pixel art involves suggestion on the part of the artist and imagination on the part of the player. Stardew Valley has some expressive faces in 8x5 pixels. Leaving out faces entirely just has a dehumanizing feel to me that makes me completely uninterested. Possibly that is exactly the intent and it is cleverly woven into the story, but I doubt it. Obviously people can disagree about art styles and maybe some people will like it, but GOG's curation is much less restrictive these days.
This could be the reason why the characters are devoid of any facial feature, as the developer/artist may not feel competent enough to pull it off. Especially for all the expressions that (I guess) may be needed in such a games like this, with such a small space to work with, and I suppose once you have committed to including them, you have to go the whole hog, which can make things all the more difficult. By omitting them, they have made things so much easier on themselves and their workload so much smaller...
This is all obviously just my opinion, and I could be way off...