Númenor sank by Ilúvatar's will.

They were breaking an ancient law, rebelling against Eru, sacrificing humans to Morgoth, slaving lesser men of Middle Earth and encouraging elvish racism.

You say that, but it was not everybody on Númenor who took part in those atrocities and crimes. Many innocent Númenorean lives. Not that I dislike the outcome, flawed gods are fun.

Yeah as Ar-Zigûr mentions, it wasn't really the Valar that did it.

Such is the payment of evil- it often never leaves innocent alone. But the evil would grow too much and the innocent would become more.

I find it hard to believe that Eru or the Valar couldn’t have dealt with the evil without destroying an entire culture. They are gods, after all.

...yes, they could have dealt with evil... by removing Sauron before he ever made contact with Númenor.

Oh yes; sacrificing the Faithful, believing in taking immortality by force despite not having it being their Gift, enslavement of “lesser” Men, etc

What was good and prosperous about it went on to build the Dúnedain Kingdoms of Arnor and Gondor