I read somewhere that the guaranteed legendary for end Act bosses were only 59<.Quote from Vaizard87
Killed Butcher after resetting and did not get my legendary. Torment II
Just throwing it out there for those looking at resetting,
Skeleton King is a bug, one they plan to fix, but put on diablo.
I agree with this, I think all end act bosses should include the guaranteed legendary as well, as said above even with this guarantee, playing through the story is still not as effective as playing through specific zones to gain exp/legs, furthermore there are legendaries that are only in adventure mode for example, the bounty specific legendaries mentioned by Travis Day in his most recent interview on twitch.
You can't "farm Diablo" because you have to reset quests to do it, meaning you need to complete every single quest before you can reset again. I honestly think every end boss should have a guaranteed legendary because playing through the game is so much less efficient than farming high-density zones that even with that it still wouldn't be as good.
that is stupid all would simply farm diablo then...
I get that it's a thing u can do if u want to, but there's no reason to not give multiple competitive ways to farm rather than if u want to actually get stuff at a decent speed there's only 1 actual thing u can do because yeah I like doing different stuff but I also like getting stuff both are part of the game.