all this talk of how "it would be soooo hard to make "last wish" and "enigma" and why did blizzard even make them cause it would be so hard" makes me think that people dont actually want a hard/challenging game. if blizzard wanted to give every single paladin defiance AND whatever their aura of choice was, they would have made freakin exiles drop in the blood moor off quill rats and zombies.
think of how hard hellmode is if you try to play it untwinked. now pvm isnt actually about if you can do it, its about how fast can you do it.
can you, just for a second, imagine a game where like three people in the entire community have an enigma? imagine if you were the one person who had a chaos, and thus were the one person with a ww assasin. everyone would think that you were some god or something. wouldnt that be a better ego trip than taking your level 342 smiter into a mld game and killing all the lower level people there because you have a duped lo and mal in your grief. if there were no dupes, it would be so much harder to make builds like bvc's and smiters. thus, the people who actually spend time playing the game would be rewarded with these so called "overpowered" items. the reason that they seem so overpowered is because they are meant to be wielded by only a few people. if everyone has a grief, its not novel anymore. if only one person had one, would the fact that it adds to smite dmg even have been discovered?
essentially, dupers have made the game really easy, and thus, no fun. people would be more judicious about using their runes in runewords if there were no dupes, and they would be more reluctant to trade them because there would be so few in the community.
I think that the battle.net experience should be more feudalist, with lots of poor people and only few rich ones, especially given diablo's medieval overtones. if there were like 25 people lucky/dedicated enough to get the awesome runewords, then, they would be like shoguns or dukes or even kings. that is the spirit of diablo, I think.
(i would like to point out that feudalism doesnt work very well, and the aforementioned could only work if the environment was completely free from bugs and outside corruption. problems would arise if any of the few powerful people succumbed to their own greed. still, dedicated people dont tend to be greedy, so if all went according to plan, the powerful people would likely have the self discipline to avoid such temptation.)