Who do you should suggest create humans then?  Or should humans
be created?
But - IMHO - kids are *MUCH* better than pets.  They are a joy to
watch grow.  The early years are intriguing and can teach us a great
deal about ourselves (both as individuals and a species).  Can't
say about the later years, my oldest (1 of 4) is only 7 (OK, lost
any possible illusion of objectivity, oh well). 
To me, having a friend is selfish.  I charish their company, i enjoy
being with them.  But i also give to them something in return, 
which feels, to me, unselfish.  The giving with children is similar,
only magnified by a google ;->  (But then again, so is what i 
recieve back from them... )
*** Over the top discussion below - please disregard if serious ***
As to the claim that children are human experiments that may fail -
Wish i could quote James T Kirk in one of his overdone speeches 
about *Risk*.  That's what we are here for - thats what makes us
human.  Thats why they built the enterprise, not to be safe, but to
explore, to seek out new life...
ken