(Before I continue with my thoughts, try your best not to lay in too deep. I get my suggestion may not be for everyone but I have looked through multiple forum threads where developers or tech-savvy individuals shoot the idea down fast but there is rhyme to my reason)
I feel like the group node is lacking various features, to be specific control over inputs.
It would be nice to be able to change the input type after a node is connected to the input.
Example: I plug a color input into a new input, the input will be an RGB picker, say I want it to be a slider, I have to plug a slider node in, delete it, plug the color input into the no slider controlled input. It might be nice just to have the option perhaps below the input name to change the type. It could be a dropdown to conserve on space and then one could easily select slider, color picker, vector, etc.
Another feature which I was researching which would be very nice would be a binary checkbox as an input option. 1 or 0, I know the quick rebuttal is, “well why not just use greater than plugged into a slider and make anything below 0.5 0 and anything over it 1!” but it can be confusing in a team environment and is honestly not always the most efficient in terms of ease of use. I personally like to make sure I am keeping everything physically based and that sometimes means the ability to see if something worked is circumstantial and what I am adding can only exist or not exist. A surface can be wet or not wet, it can have clear coat or not have clear coat, and so on. Given that I have seen the topic brought up on graphicall, blender artists, and other places, I see there is a demand for it but it typically falls to the wayside when someone says to just use a slider. It’s more efficient for the same reason it is efficient that maya keeps W, E, and R close together for translate rotate and scale, its not about being lazy and they didn’t do it to be different, but because its practical to move your hand less and that little extra touch keeps you from breaking your momentum which as an artist is super important.
I say all of this knowing full well these may not be “trivial” tasks and hopefully, my suggestion of it doesn’t make it sound like I think it is. I think this is one of those areas where the feature could bring a lot to the table and be extremely useful to maintain a consistent workflow for a lot of look developers taking advantage of group nodes (which by the way is an awesome feature).