If they hadn't found the kin, they wouldn't have found the bowl. But if somehow Nynaeve and Elayne had just magically found the bowl and vanished off, the Seanchan who landed only days later would have captured and collared all the Kin in Ebou Dar. That's hundreds of channelers, not wilders, some like Samitsu with talents unknown even among Aes Sedai. Their numbers and their skill would have been an immeasurable boon to the Seanchan.

(either that or the Black Ajah would have found them, which might well have been worse. Either way, though the Kin haven't been terribly useful up until now, they might well tip the balance at some future date. Certainly they'll be needed at the Last Battle.)