You don't have to use a JS MVC framework just because you built your core logic behind a JSON API. You can just as easily have a server side rendering app talk

You don't have to use a JS MVC framework just because you built your core logic behind a JSON API. You can just as easily have a server side rendering app talk to the JSON API instead of the directly to the datastores. You get to stick with 'what you know' while still maintaining flexibility for later.