I grew up in a family nearly double the size of yours and strongly disagree with you. Sure, it wasn't miserable or anything but I was a child taking care of children as early as I can remember and with that many kids things like paying for college becomes much more challenging.
I don't think it's invariably wrong to have that many kids, but there's no denying that it stretches resources (parenting time, money).
Depending on the culture children are seen as an investment or a cost. In cultures where retirement consists of being taken care of by your children parents often have more children. In cultures where parents are expected to take care of their kids (in terms of higher education especially) they are seen as more of a liability.
It can be ugly to think of children that way. My parents certainly did, considering each a "blessing from God" but the bottom line is that kids do require resources and the more you have the less there may be to go around.