When the plot and storyline is good, you dont even notice the voice change that much. This episode was great and probably the best of season 7 so far. I loved the concept of it. This was the first episode of season 7, which had both rick and morty for a substantial amount and I was invested in the plot. So, the voice change didn't bother me.
Also loved the message behind the episode. How ignorance is a bliss. We people always talk about humanity, morality .........but only it doesn't directly affect us. We just intentionally choose to ignore the problem when it affect our own lives. Who cares about what's happening far away for us ? Let's just enjoy our spaghetti, right ?