Human development without a doubt is a highly important field of study. Human development provides parents with a 'road map' of approximately where their children should be, at his/her age compared to their level of development.
Agreed. Especially important is the first year where major problems such as autism, hyperactivity and social norms and etiquettes are learnt. Physical development and mental/social development are both of importance. Erikson's stages are very useful here. Knowing these stages , one can be aware of the potential problems and deal with them before they become serious.