Marriage isn't 50-50. It's both parties giving 100%. Dr. Emerson Eggerichs addresses the differences in the commands extensively in his book Love and Respect and on his website, most recently in a September 4 blogpost.
This verse doesn't mean that women don't have to love and men don't have to be subject to their wives. Paul was giving instructions about the hardest thing for each group to do. Because of how women are structured, they love more easily and more completely than men do. To do the hard thing, they have to respect and submit to their husband. That kind of respect goes against the desire for lordship they've had since Eve (Genesis 3:16).
The same verse (Genesis 3:16) shows why men are commanded to love. Because of that Fall, we want to dominate at all costs. For men, love is the hard part. We want to feel respected and we give respect relatively easily, but love, that deep, pure, selfless-give-myself-for-you love, is harder to give for us. We want to say, "Love me physically, and I'll give you the emotional love you crave."
As to why children are commanded to obey, just spend time with some. Obedience is their hard thing. Obedience to those in authority is part of love (John 14:15, 23).
All of these things are love, but they are love in the way the other party understands it best.