@mb: I think the appeal of Soylent is scientifically getting down a drink for your specific need. It's ever-evolving, but unlike many kinds of food replacements, it's meant to be most or all of your meals. Meal replacements tend to be supplements to ordinary eating or temporary, while Soylent is intended to be a long term solution for you in particular. Instead of trying to replace foods, it's trying to get at the very root of chemical needs. Functionally, it's very similar, but it's more like a different approach than something completely different.
I agree, though, that a lot of this is the pitch. My brother can't eat normal food due to his disability; so, he lives solely off of a Nutren variant through a feeding pump to his stomach. He has no other food, and he has lived that way for over 13 years. It works. The big apparent difference here is in that approach. Finding a nutrition solution not because you can't have food but because you want to replace food. Functionally similar but with a different intent.
Also, I'm glad my brother doesn't have to actually taste his food replacement. Just from years of putting it in the pump and occasionally getting it on me, it's not great. ha. But it gets the job done when pumped right to him; so, I'm really glad it's around.
@mercury45: I literally just learned about that while reading what TVTropes might have to say about his death, and it just sucks that there can be someone who is so good at cheering others up, but still be so depressed themselves.
That's unfortunately rather common. It's not unusual to be able to cheer others up while feeling bad on a personal level. I struggled with depression for a long time, but I was generally known as a happy, go lucky person that was always willing to listen to others. That part of me didn't change; it was just a matter of not getting myself the help and support I needed.