Juliana Soong saw Lal's photo, found out who the girl in the picture was, and asked Data to promise her he'd never try to create another android ever again.
REALLY?! I don't remember that part in the episode. I'll have to rewatch the episode. If true, then that's a horrible thing for Julian to say to Data. Bad mom!
Data should've continued his attempts at "procreating". Even tho Data didn't find the error in Lal, he should've created another android and use different types of "parenting".
If you consider Data a sentient life form and thus any offspring he creates similarly sentient that is a grossly irresponsible thing to suggest.
One, I would believe most parents would agree with you that you shouldn't have a child if you can't ensure their safety. In this case if a child is going to die due to an error that you can't resolve on your part, bringing another child into the world you know to die would be morally questionable at best.
Unless you're suggesting that these "disposable" chlidren shoudl just be platforms for experimentation on his "parenting" in which case I'd find that even more morally dubious turning them in effect into guinea pigs. Either way I don't see it as something Data would do again until he's certain he cold resolve the issue.