Redline still works because it never tried to be overly complicated. The design is simple enough for everyday use, but the red lines give it a recognizable identity. I checked https://tattoomagz.org/best-ak-47-skins-in-csgo/ while looking at AK skins that have stayed relevant for years instead of disappearing after one wave of hype. It may not be the most original choice anymore, but that does not make it weak. Sometimes a skin becomes classic exactly because it keeps fitting many inventories.