I didn't want to post this in any of the dead-horse-beating threads about death-penalties, since I am to suggest a completely different solution to the same problem.
Instead of re-introducing death penalties, introduce a survivalist bonus to XP! Something like this: everytime you complete a quest that you get XP for (i. e. at around your level or higher), you get a tiny but cumulative bonus to your XP. This bonus can accumulate to a limit, say 5%, or maybe even as much as 10%. However, if you die within a quest, your bonus gets reduced, or even reset to 0.
Like a 'death penalty', this would cause most players to play smarter. but unlike the penalty, it wouldn't aggaravate players who are against such a penalty.
Turbine used Bonus-XP weekends to lure players into playing more. Could we use the same lure to make players play smarter?