Learning English wasn’t necessarily something that the K-Pop scene had much interest in back in the earlier days. But it seems that more and more idols are showing an interest in learning the language as they now realize how much of an impact and influence they have on not just people in South Korea but all over the world.
This would naturally motivate some of them to make time from their busy schedules to learn the language so that they could communicate better with international fans.
Of course, he did mention that learning English was also a must for him because of SuperM promotions, which is actively taking place in the US.
You can check out more about what Kai said beginning at around 43:14.