Let me try to think of casualties. Overtkill was destroyed multiple times, and Cy-Gor was killed, and now they're both zombies. Redeemer 1 was beat and never came back in that form. I believe Redeemer 2 was killed and never came back. Redeemer 3 became an ally, and is currently Reaper. And now there's also a new Redeemer with the coins/medallions over his eyes. Nyx died and now there's a new She-Spawn. Soul Crusher just died, but it seemed like he had tech that made him strong, and he never had a face, so he's easy to bring back as someone else under the mask. I'm pretty sure all the lesser demons and angels that died stayed dead.
I don't personally mind it too much, but one thing that the Spawn world has going for it as an excuse to bring back characters is that a lot of those characters are Hellspawns and Redeemers, and can have a legacy. For example Medieval died in the far past, but now his spirit resides in the armor, allowing a new character to be Medieval Spawn. Or She-Spawn having them mantle passed. Even Spawn himself, for a time.
I know killing characters creates stakes and drama, but when the story isn't succinct and has a defined beginning and end, to kill off a character feels like throwing away or destroying a toy in your toy box. Once it's gone you're not able to reach back in the box and grab it when you feel like playing with it again. If there never was another Redeemer, there'd have to be a new angel warrior created, so why not stick with Redeemer itself rather than creating a new one that's functionally the same except with a different name, especially when it's established that the designs can change. I still miss Redeemer 1 (I'm not calling him Anti-Spawn) because it really did feel like the antithesis of Spawn.