I don't think the price of failure should be death, but I don't think it should be off the table.
Plenty of genre media has heroes that can't die: Superman, Batman, the Doctor, etc. They still have stakes and a sense of loss even if they don't die (or permanently die). But it only works if your PC has something to lose: friends, allies, families, people under their protection, etc. Superman might not be physically challenged by many, but Lois and Metropolis are.
However, D&D isn't that kind of genre media. Thru aren't the defenders of a city, world, or galaxy. Some might be that kind of guardian, but they can be murderhobos with nothing they value except thier lives and their magical toys. Sometimes death is the only price.D&D could use a few more options between glory and death.