The atrocity of the Akallabêth

[Legate of Amon Lanc]

I also don't think killing women and children would be OK, but I suppose what we have are forgetting is, that possibly 90% of the Númenoreans were really wicked at that time. This would include the women as well (they could very well make sacrifices of their own children to Sauron, for example). And after all, Valar let the Faithful leave. If they acted really ruthlessly as you say, they'd have put the island down no matter if any faithful were there.
TM, you said they missed warning... I think they got enough warnings: if you don't consider their own tradition, then from the Elves, the Faithful ... and this took centuries. Ar-Pharazon was really much then. I think we'll all agree that worshiping Sauron and making bloody sacrifices of other people is really not nice. But we have many warning omens even in the last generation: eagle-like clouds from the west, restless earth beneath the island, lightnings from the skies, and here is the reaction of the Númenoreans to the warning:

Then some few would repent for a season, but others hardened their hearts, and they shook their fists at heaven, saying: 'The Lords of the West have plotted against us. They strike first. The next blow shall be ours!'

If I exaggerate it a little bit, the Valar were very kind to wait until the last moment, till Ar-Pharazon really attacked Aman. You also have to look at it from the point of Valar, or Eru - you have some world you had a hard work with, but when your own creation turns against you, who have created it for them, believes Sauron that you are just a nonexisting phantom (sorry TP ) and instead worships Melkor as "Lord of All" (when actually he is stuck somewhere in the Void), and finally, wants to attack you (?!?! huh?), that's really much. Destruction of Númenor was not exaggerated punishment in my opinion, for the "evil ones", of course. And as I said, when the Faithful left, there possibly were not too many of those who didn't deserve the punishment. So, I also don't agree that the death of those women and children was O.K., but they surely were not so many - they were not all of the inhabitants of Númenor, there were just few of them, so the portrait is not as terrible as you show it.