Well, chlorophyll evolved for survival, not to maximize yields for human agriculture. In the wild, plant growth is bottlenecked on the availability of water and nutrients, and they tend to get way more sunlight than they can use. This is shown by the fact that chlorophyll is green, so plants are actively reflecting away most of the energy from the sun (where green is the dominant wavelength). If wild plants benefited from absorbing all available sunlight, they would be black (or, given the specific chemistries involved, probably a deep purple). In artificial conditions, perhaps one could do better.

Which isn't to say that artificial starch poduction isn't still the way to go, but even in the grim darkness of the future where we're all eating starch capsules for every meal, people will still want a tomato once in a while.