As a child I spent most of my time drawing and sketching things from my favorite comic books, tv shows. I know most 2d artists can agree with me that Dragonball Z played a role in your wanting to become an artist
. If not, then it may just be me. But somewhere along the way I lost my drive to draw. I spent more time reading and socializing and just forgot to pick up a pencil now and then. Women also played a key role. And once you stop picking up that pencil and drawing, you lose what skill you had worked up. It is not gone completely but it doesn't just come back to you.
In high school I began to teach myself 3D. And yes. I did struggle. I was trying to concept complex projects in the free 3D Program Blender and then polish them to completed projects. This was just creating a giant heap of mistakes. I eventually realized that I needed to practice my 2D art. And so I started keeping a sketchbook.
I'm going to put it bluntly. When I started drawing again. It was the single most discouraging thing that I have ever done. They were horrific and terrifyingly awful drawings. I was so disappointed in myself. I then went off to Art School where I learned the basics and foundations of art and I have been getting better and better at 2D art and it has been showing in my 3D art. I improve with both every day. Don't get me wrong. I still have a long way to go before I can stand up to a lot of you here. But it is worth it to learn the foundations.
I'm sorry for the long post. I just really wanted to augment the OP's original statement that Foundations in Traditional Art are, in fact, important in the 3D world. Even in Photography, and Cinematography. Any artistic field really. Whether you are an artist, an intellectual, a construction worker, a chef. Drawing is the best way to convey ideas. Especially ideas that words cannot explain.
So my fellow artists. Draw. Love the way your pencil dances across the paper. Love the lines you make. Love the feeling. Love the outcome. No matter what. The next thing will always be better.