We use data from network-config for interface configuration. In most cases this ability is good, but in rare cases, it may be necessary to avoid automatic configuration and do this manually after deployment.
For the native Cloud-init modules exists a special option that can control this: network-config=disabled, which can be provided using various sources, like kernel arguments, config files, user-data, etc.

We should introduce a similar thing, so customers can control behavior and disable autoconfiguration if it is not required.