I'm one of four. I can't imagine a life without siblings and I want three inshaallah. But if having one child is what a couple wants and feels they can handle best, I say go for it. I see so many people around me having children mindlessly without being ready for the awesome responsibility that it is. So in a way I appreciate that parents who want only one are so serious about the amount of time, energy, and responsibility that should be invested in a child.