My girls used to LOVE the Wiggles. I still get some of the songs stuck in my head sometimes. They did remind me a bit of the Beatles, in that each of the four members had a distinct style/personality.
They diminished the brand a bit when one of the originals had to pull out through a degenerative illness. They replaced him with his stand in. But then a couple of years later suddenly dumped the replacement and put the original back in. It was rumoured that the original member had financial problems and needed to come out of retirement. It was badly handled and affected their popularity. Then not long after that they announced anyway that all but one were quitting and being replaced by a younger group.
Not a textbook example of proper succession planning. I think they got stuck in between a perception of themselves as a genuine band, like the Beatles, and a children's entertainment concept which was less dependent on who was filling the coloured shirts.