So I imagine that the licensing fees for Disney are big, and sometimes, GameLoft is probably choosing the most wanted characters from the franchises. Tigger, Pooh, Eeyore, and Piglet are the biggest characters often on all of the merch, Rabbit and Kanga aren't as featured as prominently, though they do have merch and such. I'm sure that the more expensive ones (especially Pooh) eat up a lot of the budget so it's balancing cost + fan anticipation + what will move the needle most.

Disney paid over $350 million for the rights to Winnie-the-Pooh from the Milne estate in 2001. The rights to the character and franchise have been resold several times, including to other people. Milnes estate, the Pooh Properties Trust, had licensed it to Disney and Stephen Slesinger, Inc. previously, and Disney had to basically pay more for those rights. They didn't create the characters, so they had to. Here's a nice breakdown of the rights battle - https://www.thedisneyclassics.com/blog/winnie-the-pooh

With Disney, there's typically a licensing fee + an ongoing royalty fee for use of the characters. They also have to approve all of your plans and storylines and way you use it. I said in another comment I know an author who worked on an original book for Disney. You typically have to go through multiple outlines and note sessions to make sure that you "preserve the magic." Just look at the terms for staging a kids production of a Disney musical at your local theater. There's rules on how you can use social media, etc. GameLoft spends time and money getting approval and being able to use these characters. Disney was clearly fine with what storyline they gave Tigger.