Soylent's creator argues that it increases the quality of life benefits of food, since the savings from the Soylent diet meant that when he chooses to eat out, he can afford very good quality food and preparation.

For myself, while I enjoy eating good food, I do not enjoy preparing food (good or otherwise), and in fact I enjoy eating significantly less than I dislike preparing food. So the total event (prepares good food -> eats good food) has negative utility to me, other than the nutritional necessity.