pert:
It is true that we already had a working IDE and that this move of extracting all the non-GUI functionality from the IDE's Java code and moving it to dedicated external tools is likely driven by the Arduino Web Editor project, but it's really the right thing to do from a long term perspective.
It is clearly none of my business how the Arduino folks create the underlying code for the Arduino IDE - all I am concerned with is that it works. Just like it is none of my business whether Ford makes 80mm or 85mm diameter pistons in its engines.
And I have re-written some of my own stuff.
However I am always conscious of Joel Spolsky's Things You Should Never Do 
...R