They're trivial constructions yes. But the difference is the shift in vocabulary, instead of understanding functor fusion in an ad-hoc way, the concept can be m

They're trivial constructions yes. But the difference is the shift in vocabulary, instead of understanding functor fusion in an ad-hoc way, the concept can be made more precise, also it can lead you to find other "non-trivial" functors for instance the Hom(a,-) covariant functor or the Hom(-,a), but equipped with the right vocabulary these things are easy to express. Sure, monoids are trivial, because they are, but once you're in the categorical setting you can begin to talk about the category of monoids, monoid homomorphisms and so on. This isn't to say that CT is the answer, but I'm pointing out that it provides a way to understand more complicated concepts. Functors are trivial, but if you take their fixpoint you get ADTs. Monoids are trivial, but if you apply them to the category of endofunctor you derive monads, and so on.