Don't hate me for this response but basically because you are using a Beta version of the API. They are subject to change and could be removed at any time or changed otherwise.
So if this is something you need to have set in stone and using for production purposes, then you would want to stick to your V1.0 API.
I also know that Microsoft are shifting on some of the APIs relating to Teams and making them only available after additional licensing has been purchased. Not saying that is the case in this particular scenario but worth having in the back of your mind.