Here's why:
* Clarity: The phrase is not as concise or impactful as other idioms expressing the same idea.
* Usage: You are more likely to hear or read "as plain as day," "obvious as day," or "right in front of you." These idioms have become more conventional in everyday language.
However, it's worth noting that "as plain as the nose on one's face" can still be effective in casual conversation to highlight something very obvious. It's a playful way to emphasize how easily something can be seen or understood.
Ultimately, while not a standard idiom, it's a recognizable expression that can be understood in everyday communication.