According to second gen fans, Apink debuted back when the industry was overstated with mature/sexy concepts. People were getting tired of it and wanted something new, and then Apink debuted with a soft, innocent concept that was the opposite of what was trendy while still modernizing the concept for this new audience. That kind of reminds me of the response to NewJeans debut. From 2019 to late 2022, the girl crush concept and louder more experimental songs were everywhere. The girl group sphere was heavily overstaurated with this concept and people were getting tired of the same thing over and over again. And then NewJeans debuted with a chill yet catchy R&B track, a youthful concept, and natural makeup and people ate it up. Phrases like "refreshing" and "a breath of fresh air" were thrown around when Attention dropped. They also modernized the dying innocent concept by incorporating technology and colorful y2k to target the modern audience.
(this is also partially why I think IVE did so well, while thier chaebol concept does have elements of girl crush, it was different enough that it still separated itself from the heavy girl crush that dominated the industry in 2021)