While D:OS 1 and 2 are certainly great games, I've barely played them due to the lack of a German voiceover. BGII is my favorite game of all time and it's fantastic that a capable development studio is reviving this brand. However, after my experience with D:OS 1, I won't be buying BGIII without German voiceover, and I'm absolutely sure I'm not the only one who feels this way.
I am patient. It would be absolutely ok for me if a mediocre German voiceover would only be released 1-2 years after release and I would even pay money for a German voiceover DLC, but without German voiceover I won't play this game.