From a business-standpoint, starting off a series with some of its most recognizable faces (Sora/Roxas/Mickey/Maleficent) is practical. Jumping straight into ancillary characters, no matter how great for the hardcore fanbase, isn't smart for the target audience: casual and hardcore fans. It's why SE tends to start off a new merchandise line with Sora, because he is the best selling character of KH (thus far).
In the event these get made and are then successful, I'm sure we'll see more obscure characters be made.
How much more do we have to wait for companies to test the market with "popular" characters? It seems like this gets said every time figures come out, even with SE.
And what happens? We get KH2 Sora or KH1 Sora 20 times and never see a new character until we've all forgotten.
The only company I really trust with this is Funko since they love having franchises with a lot of characters to work with.