If it is optional maybe. But people already have their own game of this called "Dead is Dead" so you don't have to have the mechanic to actually do something like this.
Basically this. Bethesda games are all about giving the player as much freedom as possible. No consequences for any of your actions, that includes death.
While I like the idea of a more expansive hardcoe mode, I think that this would never be included in the game itself. Especially if you die due to getting stuck in a rock, or some other kind of game bug. This is easily enforceable by the 'Dead is Dead' rules.
However, there is a middle ground here. I once read that Arwen, a modder in this forum, was working on a mod that would impose significant penalties should your character become incapacitated. Basically, you never die, but your body is dumped in a random location, looted of equipment and caps, and left for dead. So when you resume playing, you have to get yourself back on your feet again, rather than simply carrying on as before.
I like this idea a lot.