Quick Balls success rate is significantly better if you play a very low amount of Pokmon, and becomes comparable or even higher than Pok Balls in certain decks, but for the average Stage 2 or SP based deck, Pok Ball offers the best chance for you to get the Pokmon you need, exactly when you need it
not a bad deal, in my opinion
It's also a 10/10 flavor win: Marchesa has dethrone in Conspiracy and becomes Queen Marchesa (and with the monarch!) in Conspiracy: Take the Crown
It's immune from damage, giving you breathing room, and it deals more damage the closer you are to losing
Interestingly, judging from various Japanese message board posts, there do seem to be arguments about what should be considered legendary and what should be considered rare, so it seems its an issue thats not necessarily localization-caused
Aaron Forsythe recalls that (R&D) knew what the future held, and we were powerless to do anything about it, and unsurprisingly, Skullclamp was banned after a few months where every deck was either running or hard countering it