Flexibility, parameterisation, re-use, variety, masses of content, small data, scalability. Endless, rich content creation, allowing smaller teams to create greater quantity of content.
Why visual editing?
Visualisation of information flow, not text based, provides immediate affordance to process dependencies, operational sequences, modular units. Playing with the way things are connected up, re-arranging functionality, and exploring your logic are far easier visually that with text. There is no compilation, no temporary variables all over the place, it is interactive, and easily enhanceable through ongoing tool improvements. The tooling and the underlying engine create an environment where you can't break things and remove the concept of a syntactic error. Another side to this is the ability to make improvements to the engine and have them apply to all procedures automatically.
Why doesn't it have an operator to do X?
Largely issues of priority and resources. There is potential to implement a huge number of useful operators, but the focus has been on a set of core fundamentals that other functionality can be built upon. The procedure system allows encapsulation of any logic or behaviour into a reusable node just like the operators. So, if it doesn't have it, build it!
Why not platform X?
For the editor, my experience is in tooling on Windows so this where my energy is best spent. For the engine, it has recently been 'de-Windows-ed' and now compiles and runs on a variety of platforms. More will come as demand dictates. Some platforms are harder to develop for since the owners require a game project and publisher before allowing access to their SDK.
I want to work a particular way, embracing interactivity, intricacy, immediacy, and play, to create games. The tools to do all these things don't exist, so I decided I would build them.