This answer from Dan Abramov explains beautifully why you would want to use redux-thunk in your application. One more benefit of using redux-thunk in your application is that you keep your business logic separate from your view part (React in your case). We had a use case where our app was written in backbone and we wanted to re-write our whole app in React. We realised that it is easy if your view and collection/models are separate. We started depreciating just the html templates and not the collections. When we deprecated all the html templates, we started using Redux in our app and deprecated our collections too.
What I want to put here is that we had our view and business logic separate, we could refactor that easily. Similarly, with React and Redux, you would want to keep that different, so that if something new comes and replaces Redux, at least you won't have to deprecate your views and you just will have to change your business logic.