First, Pokemon is mainly targeted towards children, even though the older community likes it as well. We barely see Pokemon die and only in games and most episodes, they just faint and they get taken to the Pokemon Center to be healed.
But let's say if a Pokemon dies. Will you get astonished by this? I mean, I saw Latios die, trying to protect the city and Latios merely lives as a soul in the 5th movie of Pokemon. It was pretty sad at least, but what do you view on deaths on Pokemon? Is it heartbreaking for them to die? What are your views on this? This also centers the games as well, even Hydreigon's death at the hands of Kyurem.
Some get resurrected as Gastly and that's one logic, despite some only living as a soul. I'm not saying they should die, but this is like how you feel when they do. I think that some Pokemon also died in the Manga, if I'm correct. And certain Pokemon can die actually, even when some are legendary.
Pokemon will always be a children's game, so death will never makes its way into the pokemon games. If you want an element of death in pokemon games, you could always try a nuzlocke run.
Did you forget about the Pokemon mangas? They have Pokemon deaths in those.
I remember where Gastly ressurected zombie Pokemon in the Pokemon Tower in Lavender town. and Red kept sweeping through those zombies. And at one point, Koga sent out his Arbok against Blue's Charmeleon, and Charmeleon used slash to cut Arbok in half.