This is a great way to get rid of your own stack of stuff so you can continue to build the projects that are now being built that will continue to grow and be successful.
flask-jsonify is a bit of a complicated library. It has a number of dependencies. It has some dependency issues, but it is one of the more stable and well-tested libraries in Flask. There are a lot of great features that flask-jsonify offers, so it really can be worth the slightly larger price tag.