No idea about Paint.Net but there is not a single thing i could name that I am missing with Gimp.

The only downside of Inkscape is that it doesn't properly open and save the most recent Adobe formats other than that I also have no idea why I would need anything more than what Inkscape offers.

Sure the Adobe tools have a lot to explore, a lot of buttons and options hidden in millions of submenus.

But a good portion of computer users have only a limited need for tools like this, no interest in that constant learning curve after major updates and no use for all those advanced features.

Imagine I learned using these tools 20 years ago, and while they heavily improved they still work exactly the same. Every time I meet Photoshop it 180d their design and button placements...

My point is you do not need to feature match Adobe to compete, making it more accessible alone could be a selling point.

As a counterexample, I would say Blender is even more complicated and is doing very well with the same model. Of course, it started as commercial software but still.

Perhaps this project will spend it's funding on a fork of Gimp that is more similar to the Photoshop UI and closes some of the gap in features.