He was offered and signed on to LMLMV and Love Has Fireworks on the heels of his breakout with Under the Skin -- that was a pretty popular show domestically and he got a big boost from it. So actually LYF is not his breakout show domestically (although internationally I think it was, in that it was the show that introduced him to a lot of international fans), it's UTS. Idol dramas don't have mass public appeal (most aren't even aired on tv) and are not going to better his prospects at being offered serious, prestigious work, in fact it will work against him if that's what he wants -- the more idol dramas he does, the less seriously he will be taken and considered for serious prestigious work. Idk if that's even what he wants though, it's what a lot of his fans want for him because they -- myself included -- feel like his acting skills are kind of wasted on idol dramas. I think right now he wants to elevate his status from a mid-tier liuliang to a top-tier one and make the bigger paychecks that come with that. And idol dramas pay well, especially modern ones for 2-3 months of work.
Not everyone can have a career like Yang Zi's where not only is she a top-tier liuliang but is also critically acclaimed and has starred in serious, prestigious productions as well and moves very easily and comfortably between the two spheres of c-ent film/tv. At some point, he's going to be considered too old to be doing idol dramas, so he's probably trying to maximize what time he has left and get the money while it's there -- serious shows and films usually don't pay as well, I think they consider the prestige to be part of the compensation package lol.
As a fan, I literally only have one wish for his career in the next two years -- I would love to see him cast in a Daylight Entertainment show. To me, that would show that his talent is being acknowledged by the right people and his career is going in a direction that will give him longevity and creative success as well as prestige. As comparison, Zhang Wanyi has already been in a few Daylight shows (The Bond, has been cast in Nirvana in Fire 3), when people in the industry talk about future major awards winners, his name is always included in that group. And imo, TJC is a better actor than him (although I'm willing to concede that they have very different acting styles so it could just be that I vastly prefer TJC's acting style).