Really, your complaint isn't with BG3, so much as it is with DnD. Everyone having Darkvision has always been preferable for parties. I don't personally think it's a good design choice, but that's how DnD has always worked (except maybe 4E, and nobody played that anyway).
Darkness causing disadvantage on attack rolls isn't in the SRD, nor is the light cantrip not generating light.
