The current vertical farming is in its infancy, sooner or later, new optimizations will emerge that will allow major increases in productivity(e.g. producing only the exact wavelengths of light optimal for growth, computer rationed water supply, advances in genetic editing like CRISPR, better knowledge of small-scale processes when studied in isolation such as their nutrient/energy needs, the selection and study of nutrient rich strains, how plants respond to increases in light/sound/vibration, etc). The idea that natural environment is optimal for growth is a conservative assumption that we need to replicate it exactly. There many factors out of control with natural environment that we apply pesticides, fertilizers, greenhouses, soil tilling, herbicides and weed removal, etc. A closed vertical farm environment will allow much cheaper overall control over production process.