Here's why:
* Monotone literally means "one tone" and refers to speech that lacks variation in pitch, volume, and rhythm.
* It can make the speaker sound boring, uninterested, or even robotic.
* While some speakers may naturally have a flatter intonation, monotone speech is often a result of nervousness, lack of preparation, or simply not engaging with the audience.
It's important to note that a lack of inflection can also be used for specific effects, such as in certain types of poetry reading or when conveying a sense of seriousness or detachment.