I think the answer is that well known and influential looters want it that way because that maintains their Thunderspine at the top of the cutlass pecking order. I also think that the game should move towards having the best cutlasses and sabres be higher dps than the best broadswords.
If you think about, thunderspine is easier to get than Jack Sparrows blade because you can only get Jack Sparrows blade from one enemy while when you're at tormenta or rc, you can group something like 5 red tag enemies and kill them all at once and you can get a cursed legendary from almost any enemy on tormenta and rc
Although the rates for skull chests and chests are higher for bosses than normal enemies so it sort of evens itself out.
That is true that the drop rates for chest and skull chests are higher for bosses than normal enemies, but like I said, you can get thunderspine from pretty much any enemy at tormenta and rc. If you're only killing something like one or two regular enemies at a time then yeah, it would even it out (assuming that there is a group at the boss to make the looting faster). But, if you're grouping multiple enemies and killing them in seconds, you would (probably) have a higher chance to get at least one skull chest from one of those enemies than you are from a boss. When I was looting at Forsaken Shallows I was grouping up to nine enemies at a time, and sometimes (emphasis on sometimes) I got up to three skull chests to drop after I killed one group of nine, and that was by myself. If you add another pirate or two to that, the kill ratio would be higher since you can kill them faster than one person can.
Somewhat off topic but I am very curious, how did you manage to group up nine enemies at a time? Would love something more efficient and engaging than siege at gold room for a change.
I forgot which server I was at but at some server at Forsaken Shallows near the shipwreck you see before you meet Koleniko, it was pretty much all thrall captains and seabeards and they were close enough that I was able to group them in one area.
The blade stats was never in the Disney's code. - All theses stats you saw were directly created by the TLOPO team...Well I found this blade without knowing it's properties, only knowing that it was Jack Sparrows Blade as Disney named it and so obviously must be a Very Special Legendary item... after all we got all sorts of obscure personas in the game with very powerful Legendary associated with them but this is Jack Sparrow himself! Around which this whole game and Universe revolves
Of course this sword is now a let down and makes no sense being so "weak"... I think the problem is that some people do not understand the "source" of Jacks Luck and his abilities in the movies and hence the power behind some of his items, Jack has much Juju most of which has not been explained.
What Disney and the Dev's forgot to write on this weapons' card is that it is a "Charmed Weapon"... what would make sense for this amazing Legendary item (regardless of who it drops from... maybe just frequency) is of course at least Crit 4 "Jacks Luck", a much higher attack maybe 92 (Drop the silly powerful thing or really make it work) and a special ability - so as we know Jack can Beguile so it could have Confusion Rank 4 (have to work that one out) or maybe Life Drain Rank 2 and then it would be the "Charmed Weapon" it always was right from it's Creators & Developers inception.
Give Jack his Luck back! Or I could say something else
Yeah... well it feels weak and I'm always comparing it to LSOEP and others, it has no spark and at the end of the day I just wanted to have my 2 cents worth supporting those that feel the same way
Ah, I see we're reopening this old wound today.Well I found this blade without knowing it's properties, only knowing that it was Jack Sparrows Blade as Disney named it and so obviously must be a Very Special Legendary item... after all we got all sorts of obscure personas in the game with very powerful Legendary associated with them but this is Jack Sparrow himself! Around which this whole game and Universe revolves
Of course this sword is now a let down and makes no sense being so "weak"... I think the problem is that some people do not understand the "source" of Jacks Luck and his abilities in the movies and hence the power behind some of his items, Jack has much Juju most of which has not been explained.
What Disney and the Dev's forgot to write on this weapons' card is that it is a "Charmed Weapon"... what would make sense for this amazing Legendary item (regardless of who it drops from... maybe just frequency) is of course at least Crit 4 "Jacks Luck", a much higher attack maybe 92 (Drop the silly powerful thing or really make it work) and a special ability - so as we know Jack can Beguile so it could have Confusion Rank 4 (have to work that one out) or maybe Life Drain Rank 2 and then it would be the "Charmed Weapon" it always was right from it's Creators & Developers inception.
Give Jack his Luck back! Or I could say something else
Oops... say no more (I guess I foolishly picked up on the Beta aspect and just hoped for something different in the future maybe... silly really, everyone's got so much to do, it's the last thing anyone needs is to look back at minor issues... apologies) 
No apologies required from you mate, just got sick of hearing all the kvetching on this topic. Chalk it up to "not every software design decision is a great one", although somehow those not familiar with the concept don't seem to allow for that. Chalk this one up to "lessons learnt", to hopefully to be a guide if we go down this path again.
The blade wasn't intended to be an "End all be all" weapon like World Eater Blade or Leviathan, it was meant to be a powerful sword you can loot if you're below level 30.
