While from a financial standpoint this would make sense, most of the guys making the executive decisions at Apple are design focused and oriented. Dropping the headphone jack differentiates Apple even more from its competition, makes the phone sleeker, helps with water proofing, makes the wireless headphones more appealing (which not only act as headphones but also communication devices). This was much more than just a financial move for Apple, and in my opinion it looks to be a smart one.