The combination 懒惰 powerfully conveys that laziness is not just an action (or lack thereof), but a deep-seated quality of the heart and mind.
In Chinese culture, diligence (勤奋, qínfèn) is a paramount virtue. There's a famous proverb, 勤能补拙 (qín néng bǔ zhuō), which means “diligence can make up for a lack of natural talent.” 懒惰 is the direct antagonist to this core value.