Izo and ashura didnt deserve to die like that with no acknowledgment really. Kinemon and most other scabbards would have had such much more of an impact, and probably deserved to die the way they were damaged. Lets absolutely add pell to this list. Ace was necessary to die for Luffy's development, but he should have damn showcased incredible haki to be 2nd commander, fight jimbe for 5 days, but then lose to blackbeard in 10 minutes. Big mom and kaido should be dead but we all know theyre not. big mom even drowned in the ocean and should have died because no one saved her prior to her fight. I absolutely love the manga, but deaths and non deaths are a joke in one piece