Unfortunately for the patient, these procedures only help your doctor's bottom line. They don't necessarily help you, and they can be harmful. In general, cancer surveillance for early detection has been a big flop -- colonoscopies included. There are plenty of people who have posted here who were lulled into a false sense of security because the doctor didn't find dysplasia -- only to find out they have (and have had) cancer for awhile.
Cancer is rare; surveillance for its early detection is a crap shoot. We wouldn't allow any other service provider -- lawyer, mechanic, plumber -- rely on such questionable procedures for such limited benefit, probably because we bear the cost out of pocket. Personally, I would be wary of any doctor who couldn't conduct his or her practice within established guidelines, such as those that warn against endoscopy to visualize the disease (treat the symptoms), or those that require 30+ biopsies to check for dysplasia (too time consuming for many GIs).
Here's yet another recent article about this. We'll be seeing more of these.