A friend of mine who owns an Allstate agency said that Agents get paid the most on new policies, so they are pushed to bring in new business as much as possible. I am not sure if they are paid a commission on renewals.
When I switch my motorcycle policy from Allstate to Progressive it made no difference, my rates dropped from $500+ per year to $120 per year. Allstate who only ever increased my premium year over year was a joke. Progressive, not only had better rates for 100% the same coverage, but also has dropped my rates by an average of 10% each year at renewal the last three years.
Just switched my car insurance from Allstate for the same reason, ever raising premiums despite the fact that we have no losses, no new cars and no tickets. Switched to another carrier, actually increased my coverage, dropped my deductible and still lowered my insurance by 25% per year.
IMHO it pays to place the insurance game and shop around.