So anyone who uses the "there are lots of subtle ways of acquiring nutrition deficiencies and we might not know everything that one needs" argument against Soylent would first need to show why normal diets would avoid that argument any better.
Not sure how that applies here, even if we disregard the processed foods that many people live on also being quite unnatural.
Rob Rhinehart's food replacement Soylent now has a crowdfunding campaign.
If you're interested in one or more of these benefits, send in some money! There is also a new blog post.