I am Ashlynn The Pogues are a great band but most people really only know that song and maybe one or two others.
I think that a lot of people just dislike Shane MacGowan for various reasons.
Apart from that they aren't a band that gets a lot of radio play (maybe that's different in Ireland), Celtic punk isn't really a big genre and some of their lyrics are a bit dark, so they aren't overly accessible maybe.