Personally, the answer is simple. As humans, we are not minimalistic. We are boundlessly complex. Lines and angles are not straight. Colors are never flat. And in terms of a grid, we don't ever require one.
“A little conflict can create a lot of creativity.” ― Richie Norton
Lo-fi design, or if you will, complex design serves an important purpose in our society today as well. Design always has an intention, and the beauty of complex and humanistic design is that it evokes a deeper emotion than a minimal design does. Minimalist design serves a crucial role as well, delivering and showcasing information easily. This is done without anticipating an emotional response to the design.
In design, and in most every profession, every style and approach has it's place. Lo-fi design can reach more of an emotional response by utilizing the more organic, and human side to design. Minimalism can convey a message or idea easily. It's the Beatrice Ward theory of the crystal goblet, but sometimes you need a golden chalice to get your idea across. Complexity breeds creativity, and creativity requires a message to convey this idea. It's all neccesary.