The primary reason for using uncuffed tubes in pediatric patients is that their tracheas are smaller and more susceptible to damage. The airway of a child is more pliable and less rigid compared to adults. Therefore, using a cuffed tube can lead to complications such as tracheal stenosis, mucosal injury, and post-extubation stridor. Uncuffed tubes minimize these risks and are generally considered safer for short-term airway management in children.