I can think of several reasons people would get upset about this, though I knew next to nothing about this woman before this post.
The world as a whole is extremely overpopulated, and there are so many kids out there that need loving families that it is ridiculous. This next one depends on how old the kids are and how many of them are still in the house, but it takes a lot to raise a child, and not just financially. Children need a lot of time and attention, and I could see concern as to whether or not that many children can get enough time and attention from their parents as being a valid.