I'm not in any way saying that traditional music or any other part of Gaelic culture isn't a valid thing to preserve and treasure or that these things aren't good ways for people to get interested in the language. Some people however will never come into contact with these things and/or they may just not be interested in them. But some of those people might be Ed Sheeran fans and may become interested in learning Irish Gaelic because of the song.
Along similar but different lines not everyone who speaks or is learning Irish is going to be really into traditional music at least not all the time. I have to admit to having days where all I want to listen to is pop music. Things like Ed Sheeran singing his hit song in Irish and all the great covers and original songs that TG Lurgan and Seo linn have done means I can listen to Irish language pop. From looking at some of the comments on the web it seems like these pop songs are really popular with younger Irish learners.
Honestly I am very jealous that we don't have more of this Scottish Gaelic. And ideally it wouldn't just be pop music. I'd love to see people using Irish and Scottish Gaelic to express themselves in every genre of music.