It improves how the sentence sounds, and gives the paper more maturity and better wording.
Let's say the original sentence was, "The little boy wept at the thought of going to the dentist, which is something he'd always feared." We see that 'dreaded' gives the sentence more weight, and conveys more emotion:
"The little boy wept at the thought of going to the dentist, which is something he'd always dreaded."
Alex could have used a thesaurus to look for great synonyms for 'feared'.