Every family starts with a nice little house, well almost all of middle class folks. They start small with dreams of building their own dream houses and castles and mansions someday, dreaming big for their family. As the family grows in numbers, more space is needed in the whole house to accommodate the need of every family member, and aside from that room space would also mean additional more room to move around, more space to place your furniture, home equipments and other stuff that you might buy along the way in your lives. Especially when the kids grow into teens, they will start to have their own individual rooms, which will automatically chew space in your home.
The best advice is to invest in a home addition project is when you are planning to stay in your home for awhile. Giving yourself a few years to enjoy your improved home is much better than doing it just to increase your resale value. This is true mainly because you can never be sure how much you will get back when you do resell. It makes more sense to invest in a remodel or home addition when you will be able to enjoy the benefits in the long run. If the primary goal is resell, stick to minor remodels.