If Leia had appeared as a blonde no leap of imagination would have been required to understand that she dyed her hair. Maybe Holdo introduced her to her stylist. Nonetheless, that would have felt unnecessarily distracting.

With Yoda, the all around lack of ghostliness similarly stands out as unnecessary inconsistency. It’s a minor thing and I don’t understand the explanation for it provided in that article for this aesthetic decision. I think a more ghostly-looking Yoda would not have felt less real to the audience.