Only if they were really stupid. Following utilitarian values shouldn't, all else being equal, lead to terrible consequences.

(I was mostly thinking about the “and probably shouldn't have children altogether” part rather than the “you shouldn't spend all your money on your children” part.)

As I said, "never having kids wouldn't be a strategy you follow dogmatically -- if too many people started doing it, it would no longer be a good idea."

Right now, I think money is better spent with first-order regard to utilitarian values on causes other than children. But I could see strong second-order reasons for children (keeping oneself motivated, some situations where the child could be a good successor, etc.). You could also not want to be utilitarian on this particular issue.