I'd like to offer an alternative point of view of Soylent:
It's difficult and time consuming for people today to eat an appropriate amount of healthy food. Meal replacements, such as Soylent, let you set a routine of (hopefully) nutritional food that's very easy to prepare and consume.
For two weeks, I switched to an all-Soylent diet (using the 1.4 formula) as an experiment, and at the end of those two weeks I stopped eating it. I personally have some concerns about their macronutrient ratios (protein and fat too low, carbohydrates too high), but I agree with the vision behind such a product.
Regardless of how it's being perceived as a 'productivity-maximizer', I see meal replacements like Soylent as a means of quantifying human nutrition and making sure that it's easy to eat healthy foods.
 And I say this as someone who loves to cook.