While the prior generation Tokyo Tower remains standing and still draws its own share of tourists, that development was more for TV purposes, with only a small shopping/dining area found beneath. SkyTree was heavily planned to generate as much revenue and tourist interest as possible regardless of the weather, so the 10-ish floors found at the base have more than just a couple restaurants and souvenir shops.
Like fresh fruit (in plastic packaging) vending machines.
Actually, the first three or so floors of the complex serve as a standard shopping mall. There are the usual clothing and accessories stores, the usual mall restaurants, and so on. There's a Disney Store and a store for Studio Ghibli. There do seem to be more shops selling souvenirs, though the fourth floor is designated specifically for souvenirs. Next to the McDonald's, we found a store for one of the major TV studios with all sorts of goods relating to many of the popular Japanese TV shows.
There's also a popular aquarium, a planetarium, and the relocated (and refocused) Postal Museum Japan. Many restaurants are found on the sixth and seventh floors.
Granted, if you come to SkyTree, you're probably coming for the view. But you can also plan on the museum and aquarium, and if the weather isn't so good the food souvenir areas are worth a stroll to try a bunch of traditional Japanese snacks.