Actually, since the Dark One was the one behind the weather issues, and Moridin said he'd be pissed if they managed to break that, I think it was paid off by itself. As Moiraine once pointed out, opposing something the Dark One wants is sufficient justification in its own right. Also the mission itself was the framework for a lot of character growth and lessons in limitations that the Wondergirls had not previously encountered, having achieved some fairly rapid, spectacular and unprecedented success right out of the gate. The plodding along and searching is one of the few examples of them actually doing plain old boring work in the whole series. That mission also reconciled the important women to Mat which probably enabled Elayne to work so well with him in the aMoL books, as well as, of course, setting him up to meet Tuon. It also facilitated the development of Elayne's and Aviendha's relationship, which led to bonding Rand, and who can say how that helped him survive Tarmon Gaidon. At the very least, they probably kept anyone from putting a pillow over "Moridin"'s face while he was comatose, and the bond probably gave him just enough strength to escape the Pit of Doom, and give the title of the chapter where he had his Dragonmount revelation, the bond probably reminded him of love and all that crap.

Without their time working together looking for the Bowl, Elayne & Aviendha might not have developed their relationship sufficiently to want to adopt each other and who can say how that would have affected Elayne's decision to share the bond, much less working out the capacity? Those are just some examples of things that happened during or because of the Bowl search.