To keep it simple, it's a pretty critical developmental skill needed for success with a number of every day tasks from fine motor skills such as writing, to gross motor skills such as hitting a ball with a bat. Many individuals, with or without, a neurodevelopmental disability, developmental delay or learning difficulties, can have difficulty crossing their mid-line.
These difficulties can impact self-esteem & self-confidence, and lead to an avoidance of physical activity or structured exercise, impacting both physical and mental wellbeing.