It's not surprising that when the general public finally caught on to the new girl group sound of the hour existing the song timing it right would blow up. "Rough" does not stray from the established GFriend sound, which isn ot that far away from the Lovelyz sound either, but it's a good sound, and a streak of very catchy songs, and the only reason for one of those songs not becoming a big hit was the general public being unaware of what goes on on the barely-watched music shows. Expect Gfriend to have a string of hits while this sound is fresh to the masses.
Now you can say you want something else, but this "ITNW"-ish sound is so much better than the last time non-sexy concepts were hot, post Gee, when all new rookie grups were cutesy but with the worst songs imaginable. Even with exposure that stuff wouldn't have hit charts.
(Coincidentally it sounds like AOA CREAM might be returning to that shitty sound)