Marketing may be customer oriented; they accept the applicant's money in exchange for insincere promises of success and employment opportunities. The instructor is the individual tasked with helping the hapless wannabe achieve this success. Yes of course, if they could achieve this by approaching the wannabe as a customer first, student second then great. But lamentably some of the wannabe pilots are unlikely to make the grade, either from a competency point of view or character view point. Being customer focused rather than studnet led is, in this case, perhaps not going to do the wannabe any favours.
However I think as instructors we need to remember always that every student is a customer, and hard as it might be, do everything we can to help them achieve their aim, even when they don't. But that's what professionalism is all about. Right?