"It is not that big of a deal to translate many of the existing Arduino examples for use with PICs. I expect an include file could be written #defined most/all the AVR stuff to make it work on the PIC."
Sure, by an expert. The whole point is that Arduino is now in use by 100,000 non-experts. They do not know that include files exist. Duplicating the Arduino system would be a VERY big deal. Endless lIbraries, 100,000+ users, numerous clubs & online communities. I even know a woman who now makes her living giving Arduino courses.
Do not think in mere engineering terms. Arduino is a PHENOMENON. Duplication is highly unlikely.
Joe