Pi comes up in a lot of places. (I almost said areas...)
Well, if 120 had a different value that wasn't 120, then would the impedance of free space be different than 377 ohms because of that too?
I once had a physics professor who said that not only would he be working in units where hbar == h/(2*pi) was equal to one, he was also going to be using units where h, 2, and pi were all individually equal to one :-).
Tim.