I don't even think XP loss is the right answer to make people fear death, I do however think that failing a Raid, Instance, whatever should at least impose some sort of lock-out for a set period of time where players can get back together smash their heads together to brainstorm what went wrong instead of smashing their heads against the wall until it works.

I don't even mean anything extreme, just give everyone a long enough chance to refocus, hash out their ideas (15-20 min like Primal Cooldowns when you win) instead of pushing people to just ram into the content again without being able to recharge.

As for open world content I feel a cooldown on teleportation should be imposed, yet get dead, you wait a few minutes before you can teleport again. There has to be something, anything, to make you actually feel like death is something you should avoid...no repair bills don't do it at least IMHO.