Compound nodes are great for compacting complex material trees into one single node.
We can go from this
To this
But there are areas where compound nodes can be made more useful.
• One limitation is that assigning materials outputs to objects requires dragging a specific output from the Slate and release it on top of a single object you wish to apply the material to. Also, all shortcuts associated with assigning materials from regular material nodes are disabled for compound nodes. This means you cannot assign materials from compound nodes to multiple objects at once and the usefulness of these nodes is significantly reduced. I just realized that with multiple selected objects you get an option if you want to assign to all the selected objects. That's a solution to assigning to multiple, but I still feel not having to drag and drop is very beneficial too. I feel this feature is of course better than nothing, but it's not so intuitive to figure out. Therefore having the ability to the suggested solution below would be beneficial:
A solution to this is to have the system check if there are actual material outputs in the selected compound node, and if so enable Assign To Selected in toolbar buttons, menu options and shortcuts. If the user runs the shortcut, because there can be multiple material outputs there should be a popup menu where you pick which material output to assign to your selected objects, such as this popup menu below:

Additionally, right-clicking on a material output should give you the option to Assign To Selected, because then it's obvious which output you are interacting with.
This can improve the usability of compound nodes greatly.