Gymboree seems to have two advantages, besides the obvious cost benefit of mass-production. One is one-stop shopping. Moms shopping online will choose a hairpiece from the same site as the clothing they are buying, if possible, to save on shipping.
Their other advantage is outfit coordination. This is where cheaper grocery-store hair baubles often fall short.
It does seem that an independent girls' line like Pixyworld could benefit from having its own collection or hair accessories. My idea, as a mom of toddlers? Include an extra piece in every set of two, for the inevitable day when she loses one!