So right now my game doesn't use textures at all, only vertex colors. However many things would benefit greatly from texturing (e.g. vegetation, clothing). Adding textures means

1. Higher engine complexity
2. Much higher content creation cost

(2) is my major concern.

Anybody got any opinions/advice on this?

@lisyarus maybe take a look at Deep Rock Galactic - they only use faceted procedural textures to mesh with the low-poly style

you can maybe do something like this only with vertex colors - then mesh density will also mean color detail