guild wars 1 i played and there was no experience loss, and you could try as much as you wanted. if you were in a quest you could fail for a full wipe, but other than that death was only effected by death penalty, the game was full of death techniques, i remember one ressurection skill where you basically become the monks zombie. and another where if you die you come back with heavy damage potential.
Dont mistake me, im not saying death should have no effect on your playing. Death should be able to cause you to fail a mission, or a run. They may in fact institute something in the coming dungeons where if everyone dies at once you fail *they already do this for missions. However having consequences for death doesnt equate to a death penalty that takes your money/items/experience already earned.
GW is the perfect example of making death matter without having a death penalty, and it makes all sorts of useful techniques and skill viable.
http://wiki.guildwars.com/wiki/Ressurection
all these skills with different styles of dealing with death, in a system with a death penalty, you are really saying you are never supposed to die. So with that in mind, you shouldnt/cant develop too much around death
point is adding death penalty does not make anything harder, it just makes it take longer to get back to where you were. In DP games i have played, most of the time the solution is that the game/groups expect you to take your DP and like it. Suck it up and take R1 its for the good of the team, go sac pull its for the good of the team. Lets all go experience party for a day so we can go zombie the hell out of some megaboss.
Its not adding any difficulty, its just adding a timesink in getting whatever you lose back. And by and large in endgame situations, people will expect, and demand you to die. its a stupid mechanic to punish people for death, then expect them to die to succeed, or have situations where they can do nothing about their deaths (death spells)
Its a totally different thing to make it so that death can cause you to fail an event or negatively impact your chance of success.