From my understanding the V1 API will be deprecated eventurally. Currently we and others use this to automate insertion of API keys after a new account is created. We are not able to do this with the Oauth unless we can pass in and Agency API key when authorizing which then would allow us to populate a RPC with all the sub account under that Agency which then would allow us to map in the API keys in situations where we need things to happen dynamically.
Example. Creaeting a new sub acount and loading a snapshot thru the API then taking that response from the newly created account to update the custom values on that account. We can't do this without dynamically passing the API key from the new account to the update custom values endpoint dynamically.
There are a few othe instances we ourselves and I know many others use so I hope they consider and alternative with the Oauth by allowing us to pass in our Agency API keys so we have the option to make an Agency connection to then dynamically pass in locations we want to make the API call to.