The question unasked is how common PC deaths should be. Given the plan for modular play, it seems reasonable to set a core rules default, and include modules which alter the lethality.
The yo-yo effect is easily avoided if the cantrip instead stabilizes the character, but requires he heal from zero before being able to rejoin combat, which is the Pathfinder approach.
If I were designing the game with the objective of growing the player base, then I'd lean to core rules that carry a limited risk of PC death, and greater lethality being a module which can be adopted with full knowledge that it will mean more frequent character deaths. It's not a lot of fun for the new players to spend more time making new characters than playing the game. I'd also be focusing on the potential for loss without death - if you survive, but the task you set out to achieve is not accomplished, that is still a loss.
But I've never been a fan of meat grinder play where the players keep rolling up new characters to throw at the near-impossible challenge until someone gets lucky and makes it through. Some gamers prefer a much more lethal style, which can be accommodated through modules upping lethality. The option of a very lethal default and modules to enhance survivability also exists, of course, but the default should target enjoyment of the game for new players. To me, that's a pretty low lethality setting.
