...there is a very similar, and less practical, traditional Irish garment called a lein. It was like a mix between a kilt and a Roman tunic, with really baggy sleeves.
The leine was a long voluminous linen shirt, often saffron colored, sometimes highly embroidered. While of necessity pleated, it was in no way similar or related to a kilt or a toga. As to it's practicality, it served the Irish of all walks of life quite well for a very long time.

St Patty's...
That'd be St. Paddy's, derived from Pádraig; "Patrick" in Irish.

would it be in bad taste to wear a kilt on this most Irish of holidays?
It was the Irish that taught the Scots to make uisce beatha. Therefore, Scotsmen and Scotch drinkers around the globe should wear their kilts on St. Patrick's Day out of sheer gratitude.