Almost all cartoons aimed at kids hope to make money on related merchandise. A lot of animated shows were cancelled because while the ratings were good, they skewed toward older teens and adults that didn't buy toys. Two that come to mind are "Young Justice" and the original "Teen Titans". Cartoon Network specifically made "Teen Titans Go!" to skew younger.

This isn't a new thing, they killed off most of the Transformers in the 80s movie so they could introduce a new line of characters/toys.