I have late 2013 rMBP 2.6/8/256. I use these ports daily:
1) HDMI for external monitor
2) Power cable to keep keep rMBP charged
3) USB for external hard drive for Time Machine backup
4) Permanent SD card for extra space since I only have 256 GBs SSD.
5) Second USB for lightning dock to keep iPhone charged
That's almost everything. It seems apparent I really need my ports!
Not a Macbook Pro 2016 owner yet but here is my view (everything is different so you have to judge it yourself.
Currently using a 2011 Macbook air but before that I was using a Macbook Pro 2007
1. )I use DVI or displayport for my external monitors. Don't really want a HDMI port as this limits me to monitors with HDMI and most of the monitors I use don't have that. This means I have 1 port wasted which does nothing for me.
2) I use the magsafe power to keep it charged, going to USB-C doesn't change anything except you are losing the magsafe. However it does open up the option in the future where once more devices are supporting USB-C charger it means you are more likely to be able to "borrow" charger from someone else if you don't have your's with you.
3) rarely connects my external drive since I am using the laptop on the road most of the time, and for backup would probably prefer to deal with Network backup solutions so I can share the backup device with other computer on the network.
4) Only have a 240 GB ssd and bought a SD card that doesn't stick out but gave up using it since it appears to drain my battery on standby. Read forums that it might help to eject it before closing the lid, but that's too much for me if I have to do it everytime. so the SD card slot is pretty much useless for me and is just another wasted slot for me.
5) Wouldn't want to charge the iPhone with my laptop since it will drain my laptop's battery. If I am on the road I would use a powerbank or if I am in the office I rather plug it to a wall charger.
Like everyone has said, if the macbook pro doesn't fit your requirement then simply don't buy it.
I actually really wanted to replace my Macbook Air 2011 for a long time with a Macbook pro 13/15 but the previous model was too big/heavy for me. Wanted a machine with 16GB ram as well since I do have the need of running Windows and Linux VM for work, and couldn't justify getting another Air even with 8GB ram, so looks like I finally have something that suits my need.