Blue
Ravenous Bugblatter Beast of Traal
This is what I mean by 4e not being very good at giving you a kind of game with a lot of consequential dying. Even in a high lethality game that bans resurrection, the worst case scenario is usually that you roll up a new character at the same level, and chug along almost as if nothing happened, mechanically speaking. There might be some big story consequences, but, mechanically, all that happened when the Cleric died was that Healing Word got replaced with Majestic Word (or whatever).
Why do you assume that a replacement character will come in at the same level? I don't think that's RAW. (Though now that I think about it, treasure parcels break down a bit with a mixed level party.)
One "high lethality" game I really enjoyed was back in AD&D 1st ed. If you died, you rolled up a new level 1 character. With the XP system back then you'd advance quickly because you needed so much less to level compared to higher level characters (XP needed basically doubled every level), but managing to keep your character alive was a big deal. I remember after a year of play having one of the only two original characters in the group of 7-8 as a magic-user (wizard? mage?) and hitting 5th level for big money spells like fireball. Glorious day.
Now, that's not the style that I run, but I've been in games over the years where new PCs had fairly hefty penalty that becomes less important over time. Leveling-based penalties had coming one one level down, coming in at min XP for current level, or other scenario that just put you a bit behind the 8-ball compared to other PCs. Of course, these also started in editions where you would lose a level for resurrection, so it was still a level playing field.