I think the multiple TB3 ports are there just because of a differentiator and bragging rights to justify price of a premium laptop than actual intended daily use for the average user, it probably was a minimal addition to the cost once 2/4 USB-C had been chosen. Still handy for the few that actually connect 4x4k and expensive TB3 devices

to the detriment of the many who still wanted EG SD cards port not just for cameras but those that stretched their budgets to get a MBP but with lesser storage than they truly needed a SD was another easy route to upgrade of sorts for storage
Similarly USB-C has effectively capped charge capacity so those dreaming of some super pro MBP I don't see it happening unless you want another Apple anomaly with a separate charge port or some simultaneous USB-C charging Yuk
I bought my wife an HP Elitebook X360 1030 G2. Its got lots of ports, a touch screen, face view log on, touch log on, and a nice keyboard that's spill proof. It cost about the same as a 13" Apple. Its got a Cellular sim in it too.
It also has an HP power charge input but to get the large HP charger for its unique HP charge port - that costs a lot more. So HP ship the notebook with a USB-C charge point. In Australia, it ships with the USB-C charger, because HP's other charger as said its pretty costly here.
If HP is using USB-C to charge their notebooks, then maybe Apple have made the right decision... could Apple Macbook Pro uses be able to charge their notebooks with PC charges in the future? Will Apple users be able to buy cheap 3rd party USB-C charges instead of expensive Apple chargers? My wife's charger will do that now ... its a pretty ugly black charger by the way ...
The HP machine though feels quite a bit heavier than my 2012 Air, but in fact its a touch lighter. Strange that the HP 13" feels so much heavier ... At a bit over 1.310 kg, the Air weighs 1.335kg, but it feels like 1.0 kg in comparison. I've weighed both together. Hmmm ...
Now ... interestingly, the HP only has one USB-C port, and that is really its only charge port. So if that fails? You'd have to buy an expensive HP unique charger. Apple have got three spare ports of course ... because Apple say you can charge from any of its USB-C T3 ports. So ... the four ports do give flexibility, and reliability, and convenience if you forget your charger.
Another point with the design, is that I cannot see why you could not run parallel USB-C ports, which would allow a higher charge rate in future high consumption machines that you mentioned. Further, with two ports on each side, 3rd party makers can use both ports for docks, which would aid dock stability. And with charging future models with high charge demands, you could have a charge device that attached to two ports, and with the twin port on both sides, they can go on either side ... you could run a dock and a huge charger with later high charge models.
So perhaps, the four port design has some logic and flexibility.
No camera card port sucks though, but IMO, not as far as a second drive goes. With the speed of the port and the low cost of drives, I don't see card drive as a valid option. And they stick out too.
The new model macbook pro does feel light ... I have wondered whether the principle of the Air, where it feels lighter than it weighs - is a reason behind the Powerbook Pro's obvious compromises.