What happened to Sm title tracks ?

[YooJeong]

SM Title tracks have always been either very very good or very bad. Hardly are their songs just "mediocre" they're usually polarizing one way or another. Example:

Red Velvet: Psycho vs Zimzalabim, Bad Boy vs Really Bad Boy, Peek-A-Boo vs Rookie, etc. 

You may not personally like Psycho or Bad Boy, but can't deny they are big hits and most people like them, while nobody really would  call Zizalabim a hit or a "top" song, though stans may say  it's a "bop"/some may like it but the majority does not. 

Just depends.