My honest opinion is, he was popular before only because of all the heavy promotion he got by being a part of 4+1. He's more popular now because one, Rang Ngao is a well loved lakorn from the previous version so with all the hype and fever for this new version, Ken highly benefits from it. Two, because viewers now a days are very shallow where they care more about appearance and less about acting so Ken also got another lucky shot. There's many examples already where it was the fans who created hype and fame for their daras and Ken is one of them. To be fair, he did somewhat improve in RN but his acting abilities alone is not worth the amount of attention that he gets today. If his lakorns were promoted regularly, I doubt he would even be here today.