I understand that we strive for safety, prosperity, comfort, and long life. But what does it mean to strive for dullness?
We all strive for safety, prosperity, comfort, long life, and dullness.
Dullness, as described by the Free Dictionary, has several senses. The primary sense has the synonym "boring." There is a second sense which means "stupid" but in the context cited, "boring" and not "stupid" is the intended sense of the word.
Dullness is not a word with a connotation as positive as "comfort", instead it is merely a lack of excitement.
The sense of the entire phrase is akin to the allegedly Chinese curse: "May you live in interesting times."