Bloodlines, FNV, Arx Fatalis, System Shock 2, Mass Effect, FO (talking heads), Arcanum, JA2 are some games where voice acting added drammatically to the game, and helped define it and stand much higher in some cases (whether along or despite the quality of the rest).
Some games are simply meant to be voice acted. These games I can not imagine without.
I have often wondered whether I would enjoy FNV and Underrail more without all the crafting, though.