As you say, you are entitled to your opinion too. I'll grant you that "thinner" requires design engineering to work out the miniaturization. However, spread that added cost over all units and I doubt that it makes the unit cost here more expensive than recent "thicker" MBpros... especially when stuff (tangible parts and battery) gets to be jettisoned to help accommodate it. But, even if I'm wrong about that here, the price hike should certainly more than make up for the added R&D cost spread over all units.
Again, that too is my opinion which one can easily take a poke at since I'm not an Apple insider with evidence of how much each unit costs (but then again, neither- I presume- are you). However, I find it easier to imagine that the genius of Apple is smart enough to have noticed the seemingly building perception that "thinner is thin enough" several years ago. And no one doubts that Apple loves to maximize their profits in any way possible. So if they know we consumers don't desire "thinner" at the cost of consumer utility, why add to their costs to then try to make us like a "feature" that the bulk of us don't seem to want? Choosing to make their unit costs more expensive doesn't seem to be a modern Apple-minded thing to do to me.
Why does THIS thing from OWC exist? OWC believes there is sufficient market that would rather "thicken" the newest MBpros (likely voiding any warranty), rather than juggle dongles & added disc drive, etc. as separate parts... and PAY up for that on top of the new higher price for the MBpro itself. OWC could be fools here and nobody wants common use ports & added storage "built in" that badly, but then again, see the kickstarter story I also referenced. Apparently some of us do want common use ports built in bad enough to commit to buy something that we basically only hope will be built.