Stating that a bit of chlorine isn't bad for a fish, is like saying that a bit of cigarette smoke isn't bad for your lungs.
Chlorine dissipates as it runs through the water mains, and depending on where you are situated from the source in your town/city, and how much water you remove at each water change, you 'might' be able to go without adding a water conditioner.
If you have chloramine in your local water supply there's really no getting around using a water treatment. Chloramine can retain it's full strength for several weeks. Chloramine isn't "worse" than chlorine, you simply have to deal with it in a slightly different manner.
Water sources & additives can fluctuate through the various seasons,and some areas may use chlorine during the Fall/Winter months, and chloramine during the Spring/Summer when the bacteria numbers rise. Keep this in mind when purchasing your water treatment.