What is the most important reason to avoid severe turbulence at low altitudes?

Avoiding severe turbulence at low altitudes is primarily focused on the risk of loss of control leading to a ground strike. At low altitudes, an aircraft is closer to the ground and has less room for recovery maneuvers if it encounters severe turbulence. This situation can become critical, as the pilot may not have enough altitude to regain control, increasing the chance of a crash due to an inability to manage sudden changes in airspeed and attitude caused by turbulent conditions.

While increased fuel consumption, unpredictable weather changes, and potential damage to the aircraft's structure are also valid concerns with severe turbulence, they do not pose an immediate and life-threatening situation as the risk of losing control does. The emphasis on avoiding turbulence at low altitudes is primarily about ensuring the safety of the flight, which is why loss of control from turbulence is highlighted as the most important reason.