Clarity and all-day vapeability. Multi-fruit ice blends impress on puff one and wear out by bottle three; a clean single fruit stays likeable, which suits how people actually vape day to day. It also makes picking painless: buy the fruit you like eating.
Very, and cheaper than nearly every alternative: a 20mg bottle plus a basic pod kit undercuts a week of devices. The flavours are calmer than typical disposables, which most people come to prefer within a bottle or two.