Well yeah I still think the BD king at least somewhat needs the ability, just on the basis that with no special abilities for the starting king, it just makes sense to kill the first king ASAP if he brings nothing to the table that the next king won’t have. For the most part the table as a whole has a 2/3 odds of being BD, while the king has a 1/3 chance of being BD, it’s a safe smart first kill.
That being said if it’s moved to just to detect unseen/cult. which don’t lose the second one of their members is detected. It’s a more beneficial all around gameplay mechanic. It isn’t utter what are the odds for a king to go 4 days without finding 1 neut/unseen. because he’s looking for 2-3/15 targets, instead of 5-9/15 possible targets. It isn’t unbelievable to not hit a cult, it is unbelievable to not hit a cult or a neutral.