I have always loved this song, and sung it many times. This has been a really interesting read. The discussion reminds me of a point an old friend tried to make with me years ago. We were locked in one of those endless arguments about "folk" vs. "commercial" songs. He argued that, particularly with respect to Irish or other traditional music, you can see it from one of two perspectives.

First, the words of songs as they reflect history and belief, whether composed or handed down over time. There are passions connected to this that transcend melody or form. I studied folk music as a sort of vernacular literature in two college classes I truly enjoyed. I see and understand why following the evolution of a song such as Roddy McCorley occupies many of us.   

The other study is the musical one - certain songs become popular because they were friendly to the ear, lyrical, memorable or done by someone who helped make them so. In a few cases, you can have it both ways.

Sometimes, a song such as Roddy McCorley becomes widely known simply because of a popular recording by, in this case, The Kingston Trio in the 1960's. The Clancy Brothers and Tommy Makem gave The Risin' of the Moon and The Auld Orange Flute wide exposure, along with a lot of other Irish songs not widely known outside Ireland prior to their time.      

I am often fascinated by the history of a song, the tradition from which it comes and so on. Selfishly, though, most performers need songs that make a connection with the listener. In that quest, the musical side usually wins out. Audiences, especially now, don't have the patience to endure a history lesson. They want to be entertained.
I guess that is why "traditional" folk music is, and has been, mostly done in more intimate venues and not for larger commercial audiences.
I don't think that's at all a bad thing.