Actually you could consider it a Greek Unity day, when you think of it. The NPC was founded so that sororities (women's fraternities) recognized the existence of one another and to promote friendship (unity) and other shared things among us. It was meant to take a step away from the whole "my org is better then your org" thing, etc.
Remember any org. can pretty much petition to join the NPC. It is up to the board to decided to let them in. NPC didn't start with 26, it grew to it and hopefully will continue to grow.

Yes, it's NPC day but only because the conference chose to have a special day. However, my 2 cents is that if your IFC. NPHC, Local, Prof, Academic etc, feel more then free to wear your bagde March 1st. It's promoting your org., unity for greeks, and supports the NPC in their cause.

Ok, back to work!