This need came from some people in the community and Dennis Ju.
Sometimes we need to execute some logic the first time the module is loaded. We can achieve that in non-regular modules with an upgrade process but in Service Builder the path 0.0.0 to required-schema-version is used for the initialization of the module's tables. Apart from this, by definition upgrade processes shouldn't be the place to add logic during the first startup.
One of the requirements should be that tables are already created when this new process is launched.
Another option is to use verify processes for this but they have to be untied to the upgrade process and be only executed on-demand or during the first startup of the module.