That is a good question but half of the answer is that it usually comes down to the game's revenue and stock restorations in stores. Now arguably they can create more figurines if they want to, but when the stores have lots of water traps and they do not want to have anymore of them to sell off the remaining ones, The manufacturer would call off the stocks until they said they can. That prevents the uncommon yawn traps to be distributed in most countries and alienate the collectors from buying anymore Skylanders.

What they should go for is not to do annual releases and do a three-five year plan, keep mass producing the toys and give the customers time to get the characters they want. If that was too much for the budget, why not make the characters digital in stores. If some figures can give you DLC, they should let it become digital so it would not become unplayable in the future.

It is a bit much but there are ways to save Toys to Life without having the game made for it.