well, let's face it, they are using an area that has for years been given over to domestic stock to create a number of small mammal exhibits, so I would argue that, if you view the name 'children's zoo' simply as a piece of marketing, ZSL are actually reclaiming most of that land back from the domestic stock that it had there. It's just a larger, more interactive version of the otter and meerkat exhibits they opened a few years ago by the clore....far better than subjecting some cows and sheep to year-round sand yards.
as well as there being an element of either coincidence or nostalgia going on in the plans to have aardvarks there again, I seem to remember an old, open-air exhibit for red pandas between the old children's zoo and the elephants, basically a circular wall surrounding a tree.