"if the reason were purely playstyle preference or personal challenge where the characters deleted for dying, they could've just do that themselves anyway, nobody against that idea. the delete button is right there."
This is true, people *could* just delete their characters. But, if you have ever played hardcore in this manner, you would know that most people simply start using that character as a "non-hardcore" character from that point onwards. Which is fine. They know, going in, that their character won't actually be deleted when (not if) they die, and very few people will actually delete it (their perspective on playing hardcore is determined by the game, not by their self discipline). So while you are correct about this, I think the point I and others were eluding to is: having true fear of death, one life, no choice about it playstyle. And this could just be a preference thing. But in my years gaming, I've seen the former to be true. Most people will just keep playing their "dead" characters as non-hardcore characters when (not if) they die.