@Jeroen-Bakker / @izo – I’ve tried to read back in the thread to see if this was discussed but I haven’t found it, so just adding this perspective for you as you develop new features in case it has not been covered already:
Currently, the compositor in Blender is not as useful as an external compositing application mostly for an easily-solved reason: you cannot quickly use it as a 2D->2D compositing app. What this means in practical use is that you cannot quickly and easily open a new scene, import a few 2D elements, composite them, and render out different 2D elements. You often need to mess around with Blender’s 3D environment to get what you want in the Compositor, and then rendering out multiple 2D elements takes a lot of juggling in the render settings. Also, you cannot easily render farm a .blend whose only purpose is to do some 2D compositing, especially if you want to render out multiple elements such as a composited beauty render and some custom mattes for use downstream.
This could be very simply solved by decoupling the main Blender render settings from the Compositor’s settings, perhaps by adding a Render node that allows one to set resolution, file type, bit depth, color, file path, embedded render layers, etc. per output, so the user can define multiple outputs from a single comp setup.
If this has been discussed and is being solved already, I apologize for not finding it above!