More than likely, the reason they're so good is that he approached them correctly. He was dissatisfied with the crap he was reading to children and determined that he could produce something that wouldn't condescend:
Nearing midlife, Mr. Jacques (pronounced “Jakes”) took a job driving a milk truck in Liverpool, where he was born and lived to the end of his life. On his route was the Royal School for the Blind.
Invited in for a nice cup of tea one day, he volunteered to read to the students. Over time, he grew dissatisfied with the books available — too much adolescent angst, he later said — and vowed to write his own.
He wrote what he called “a proper story,” brimming with battle and gallantry. Titled “Redwall” and published in 1986, it became the first installment in what is now a best-selling 21-volume children’s fantasy series.