First, in the movie, only the 'green' variant of Soylent was people earlier versions had other starter material.

That said, this product is designed for people who don't cook, don't care what their food looks like, and really would rather it didn't take a lot of time to prepare and make much mess. Oh, and people who believe in the apocalypse but they have their own issues.

Personally I like food and eating as recreation way to much to eat this stuff, but there have been times in my past when I was heads down in some project and eating was sort of an after thought. This would be ok in those times.

The concept is not original, there are various sorts of manufactured foods both for folks who are starving, and for folks who are otherwise incapacitated (like in hospitals) but this is the first version of that sort of product for general consumer use.