Personal feelings are not - and should not be - part of business.
Business are run by people (otherwise known as emotional beings), and the products they sell are purchased by consumers (emotional beings) and if you neglect certain facets of selling such as emotion and loyalty then you risk alienating customers. The business world is rife with missteps because companies looked purely at the numbers and failed to consider the emotional impact of that decision
As I said, Apple is very image conscience and that is a fairly abstract concept compared to ROI. Slightly off topic but consider the time Coca-Col altered their formula. From a numbers perspective it probably made sense because sales were falling but it turned out to be one of the biggest blunders in history.
Back to Apple, they're focusing on consumers who are a fickle bunch, if there is a perception of design flaws, missteps or problems, they may very well be more hesitant to buy a newer model out 6 months later.
Its not just checking off a ledger sheet to see if a decision makes sense, Apple needs to consider short and long term implications that are beyond a balance sheet.
Finally the 2016 model has been extremely successful for Apple why change a successful product midway into their life cycle, that from a numbers perspective doesn't add up. Up until the release of the new MBP, sales were dropping and they were losing marketshare, the latest quarterly results shows a reversal of that trend.