The reason practical life activities are important is that they help your child develop order, concentration, coordination and independence. It's not "just" getting dressed, "just" juicing an orange or "just" cleaning the floor. The child is learning to follow a complex motor sequence, independently, in order to fulfil their own desires and needs. These skills, when taught early in life, allow children to believe in themselves as well as they develop the self-discipline needed for success throughout their lives.
Every exercise of practical life must have a purpose. The purpose must be understood by the child or the exercises become boring. For example, before a child can help bake cookies, they should know how to sift the flour, crack and whisk eggs. These skills are learned and practised separately, but the child must know the purpose of the exercise they practice otherwise they wouldn't feel as a worker.