I really don't understand Soylent. Do people really hate eating so much? Eating is one of the greatest joys of human existence. I understand that people have other things to do, but are you really so busy you can't sit down to enjoy a good meal?
It's not for every meal. You'll still want to go have dinner with friends or family, but during the day it would be nice to chug a glass of this and keep working; hands clean.
Ensure (etc) are aimed at medical uses. That's because most people find the idea of liquid feeds weird.
But if you want to live on liquid food there's nothing to stop you using Ensure, even if you're a fit healthy active person.
I love food. But I hate being forced to partake of it 3x/day.
Having said that, I don't get why the current geek love for Soylent when there's really no shortage of meal replacement shakes out there that seem to do the same job but cheaper. I also love actually eating food, so would only use a shake for a short term goal.
But before you get too far down this rabbit hole, consider that people's eating habits occupy the same emotional space as religion and politics.
In other words, it is possible but unlikely that you'll be able to argue someone out of their position on any of the three topics.
In the long-run, I think it will save me time, and more importantly, improve the quality of my time. To the extent that I'm trading time spent standing in line at a food truck on lunch break in SOMA for time spent researching nutrition, I think that's a good trade.