[arm-allstar] Why Arduino?

[Thor Wiegman]

The Arduino thing sounds cool but it leaves me with a question:  Why use 
an external microcontroller for this instead of the Raspberry Pi's GPIO?

I've been hacking and slashing on the simpleusb channel driver (I'm not 
a programmer, what I'm doing is ugly) and had planned just to use the 
GPIO pins for COR and PTT.  But the Arduino project makes me wonder if 
I'm missing something.  If its not possible, or not advisable, to use 
GPIO for this then I'm going to waste a lot of time and feel really 
stupid.  Again, I'm not a programmer so I'm sure there's something I'm 
not understanding.

Thanks
Thor