It's not only a question of time,it's also a question of energy and focus.
Soylent is not for everyone, but imagine you are a college grad, who just got a good job that finally pays and you want to make sure you build a good career.
Many college grads also need to focus on friends, dating, finally trying to find good exercise to become healthy, everything while working 60+h a week.
Not everyone has their stuff figured out, many young professionals are struggling, due to little money, social anxiety, job troubles and many of them can't cook.
Now tell them they should cook something every couple of days and that they should learn cooling for that when they can't even get their problems straight by themselves right now.
Soylent is not for everyone, but it is a big help for young college grads who are barely
scraping by and who don't know how to cook. It's better than McDonalds.