I have yet to utilize the full 16gb of RAM...
Neither have I, but then I recognise that other people are running loads of virtual machines, using audio software with huge banks of samples, editing huge high-res bitmaps etc. and, yes, they
do need 32GB. Ideally, if I choose a "power user" machine that's going to last me years I'd like to leave some of those options open, so even the 2015 rMBP, with its non-upgradeable RAM, is a bit of a drag.
Replacing a USB 3 port with a Thunderbolt 3/USB-C port, capable of 40Gb/s throughput and can be transformed or daisy chained into any other port is somehow… less 'pro'?
With the 2015 rMBP you could directly plug in two displays (miniDP + HDMI), a keyboard, the charger and a TB disk drive and
still have a spare USB port and SD slot. With the 2016, there's only 4 holes to plug anything and virtually no existing equipment has a plug that fits those holes, so you're dependent on having the correct dongle or multiport dock in your bag. Yeah, that's "less 'pro'" in my book.
True, that 160Gb/s of total throughput would be great on a 12-core Xeon with twin workstation-class GPUs and 64GB RAM... but on a low-power i7 with thermally-throttled mobile GPU not so much... Probably for the best if you're going to block up some of those 40Gb/s "anything" ports with a chargers or USB3 equipment.
The problem
isn't having TB3/USB-C ports - that is essential future-proofing on a new computer today. No, the problem is replacing
all the ports with TB3 in one fell swoop, at a time when the interface is still in its infancy. Yes, I like the
option of a single-wire dock on my main desk, but I don't want to have to buy one for
every desk I use and/or to have to grub around in my bag for an adapter every time someone hands me a flash drive at a meeting. Taking the old 2015 rMBP and just replacing the TB2 ports with TB3/USB-C would have been the sensible compromise - the all-TB3 decision was pretty clearly driven by the determination to make everything thinner. The 2015 was already thin and light enough given its level of power and connectivity.
Now, if you want thin'n'crispy, the 13" non-TB 2016 is going to be great once they replace the "Pro" on the label with "Air" and shave $200 off the price.
Starting production in Q3 with Kaby lake ..... But by then, Cannon Lake and/or Coffee Lake will be out. So, Apple is going to be 1 full CPU/chipset generation behind PCs now? Way to go.
Intel is the problem here. Each "generation" consists of a large variety of desktop and mobile versions with different power consumption, clock speed and embedded GPUs, that Intel trickles out over the course of many months and often doesn't complete before the buzz for the next generation kicks off. Intel's dumbed-down and almost meaningless i3/i5/i7 branding disguises this.
AFAIK the only mobile Kaby Lake chips available at the time of the 2016 launch were the 15W ones
without the premium"Iris" graphics that Apple prefer (so not ideal even for the non-TB MBP). The various models
launched early this year (not clear if they're actually shipping) don't include an i7 HQ with Iris 650 graphics suitable for the 15" MBP.
In this respect, Apple's "problem" is that rather than emulating certain PC makers and always cramming the latest Intel chips into their machines - without really worrying about power consumption and graphics capability - they tend to wait for the Intel processor that they actually want.