The Japanese idols don't have to be picture perfect or look like an anime character. Why do kpop fans expect perfect vocals, dancing, visuals and a pristine virgin until they're 45? It's more about the persona and having fun than the music, or could be but fans take it very seriously. The fact idols are competing against real musicians and singers on the charts is mind blowing.
Taem1n is an artist and K3y is an idol. One has mastered his craft and brings a level of artistry to every concert that makes others study him, even outside of his genre. The other is a very good singer and dancer but is a manufactured act. It's why Taemin chafed in Superm and resented being pushed into another manufactured group, after several years of making his own music and being taken seriously by the industry.
I'm not trying to put K3y down. He's very talented, even at debut he was one of the best in his group. His talents at dancing, singing, fashion and variety shows makes him very well rounded. However, he's not at the level of his maknae when it comes to worldwide recognition and being able to breakout of the idol mold. One is a kpop artist and the other is a kpop idol. SHINe3 members have said they are a manufactured group.