In some cultures, it might be a given that the mother will take the lead in raising and nurturing the children and the father will be the provider & disciplinarian.
For some, it is a big deal to know what exact role they will play and what is expected of them. Some fathers are hands on whilst others may see it demeaning. Attitudes vary according to cultures and their own upbringing.
If it is important to you who changes the nappies and helps with the homework etc. Now is your opportunity to speak or forever hold your peace.