Nighthawk, considering how many different (non-celtic) cultures play or played the pipes, why do you say the Celts invented them?

In actual fact, they may (as some claim) be north-African in origin, or possibly near-Asian. There's room to argue for both, more than there really is for Celts.

I personally think the association of pipers with St. Patrick's Day (no matter where he's from originally, he is still the patron saint of Ireland and the first Bishop of Ireland) has to do with the fact that marching uillean pipers just don't look or sound that great. If you want to have a parade, you need to make it interesting for the audience. Scottish pipes are closer to being an Irish thing (same general part of the world, after all - and a share in the persecuted feel of living next door to England) than most marching bands.

There are also Irish pipe bands playing GHBs or Irish Warpipes (just a GHB with one tenor drone removed) and that might lead to a certain difficulty in telling the cultural aspect of GHBs apart from Irish life. Then, you can also find a lot of associations in popular cultural impressions of Ireland. (Scottish pipes show up in Darby O'Gill and the Little People and also in The Quiet Man, which a lot of folks love to watch around today. I actually own both and love them both.)

Anyway, that's my take on it.

-Patrick