Template based generation of artifacts helps for developer productivity in the initial phase of building the application. There are several application components, which have similar behavior and often very similar implementation.
A prominent example is Entity Service. It has several predefined methods based on REST concepts and HTTP - GET, POST, PUT, DELETE on an entity level as well as a list of all entities. Additionally, the most notable storage for the entity data is the RDBMS provided by the platform.
Another example is user interface templates based on patterns - list, master-detail, input form, etc. There can be provided also templates based on different frameworks for client-side interaction.
NOTE: The generation here is one-time process. Once you have the generated artifact you can modify it based on your own requirements.
In contrast of the approach above in case of MDA, you can expect to regenerate the PSMs every time you make changes on PIMs. For this approach we introduced the Entity Data Modeler, where you can define declaratively all the needed components and their attributes which afterwards can be used for generation of a complete full-stack data-driven application.
NOTE: The enhancements in this case must go via extensions only.