I know this is a REALLY old topic, but I've always wondered the same thing - why no lock button for the rear hatch? I had a 2013 Edge Limited, it had the hatch lock button, and I had a 2008 Expedition, also had a hatch lock button. I don't recall if my 2005 Explorer Eddie Bauer had one but I'm thinking it did.
I've had this '16 Explorer for coming up on 1.5 years and this one TINY missing feature has ALWAYS bugged me - I just keep forgetting to post about it.
Peter, you're talking about a different issue - it's not to be able to lock it from the inside of the hatch, it's basically a "door lock" button (like on the front doors) to lock all locks, not just the hatch. It's super convenient to use, as in a previous poster's example, when one is unloading groceries or cargo or the dog, etc. I'm one of those guys with a "man purse" (holds computer tablet, wallet, Rx Sunglasses, asthma inhaler and other meds and, of course, keys). If I have groceries, first thing that goes in the house is my man purse, drink, other piddly stuff - then unloading groceries. Since my keys are now in the house, I can't hit the (now non-existent) door lock button before I hit the "hatch close" button to lock the car. I either have to go to the front door and hit the inside door lock or the outside keypad (and I'm still holding the last batch of groceries to take in) OR try to remember to hit the FOB lock (which I almost always forget by then).
Since I have a $500 radar detector and iPod in the console, I'm not keen on leaving the doors unlocked - not even in my relatively safe neighborhood. And yes, when I exit the vehicle from the driver's door, I COULD hit the inside "door lock" button before going to the back - but again, my hands are usually full or I don't think of it - especially since I've had a rear hatch door-lock button in my last 2-3 Fords! Even after 1.5 years, half the time I'm still standing there A) looking for the hatch close button (it used to be on the inside wheel wells by the rear seat controls before they moved it to the hatch bottom - stupid place, really), and/or B) looking for BOTH the door lock button AND the hatch-close button! And, again, I'm usually standing there with full hands/arms!
It may sound like a piddly thing to gripe about, but when it's been there in 3 other Ford models, it truly is a convenience. (I have the door kick thing off - it never works when I want it too, then closes the hatch on my head when I didn't mean to engage it)