The MBP has a host of connection options without need for a dongle if you buy new cables.
...and the old MBP had a host of connection options without the need for a dongle
or new cables... and nobody is suggesting that the new MBP should have
zero USB-C/TB3 ports, so that would include TB displays, docks and USB-C 3.1g2 devices. It had even got to the stage where data projectors were starting to come with HDMI so you didn't even need a VGA dongle any more.
Personally, I see no real difference between a USB-A to C adaptor on the end of a cable and the cable itself.
...well, yes, that's actually part of the problem: in most cases, no advantage c.f. a USB-A cable, or a USB-C cable with a C-to-A adaptor (which usually
comes in the box with any USB3.1-over-USB-C not made by Apple). So the only difference is the $5-$30 you paid for the adapter/new cable (times however many you need) - or the fact that it doesn't work possibly accompanied by the smell of burning electronics if you got a cheaper no-name adapter because you were feeling lucky.
Oh, and in many cases, look harder: that simple, what-can-possibly-go-wrong cable is now an active cable with an ID chip and/or various strategically placed resistors or other components that has to meet a complex protocol stack. That HDMI-HDMI cable now has needs all the extras to correctly force the USB-C port into DisplayPort Alt Mode
plus an active DisplayPort-to-HDMI converter (same routine for VGA)... and when devices that support "native" USB-C HDMI Alt Mode start to appear we'll have a new generation of physically identical USB-C-to-HDMI adaptors that won't work on most existing computers. Even the USB-C to DisplayPort cables include some power conversion jiggery-pokery - its not like the old TB1/2 ports with DP++ so you could just plug a
passive full-sized-DP, HDMI, VGA or DVI in and they'd emit the right signal.
In most cases, all USB-C achieves is to combine several otherwise independent functions (Thunderbolt, USB 2/3/3.1, data, displayPort) into a single connector. Which may be great for phones (...for the five minutes between USB-C becoming ubiquitous and all phones going totally wireless and hermetically sealed) but is a pointless form-over-function complication on anything bigger than a 12" MacBook that just adds a whole new and exciting catalogue of things to go wrong along with a combinatorial explosion of cable types.
Of course, the whole idea was born at the time when the entire computer industry decided that tablets and phones were the future and nobody wanted PCs ...turns out that nobody wanted PCs
because the computer industry was ploughing all of their effort into developing and selling mobiles, to the extent of even messing up PC software to make it more "mobile like" (*cough* Windows 8 *cough*). I suspect the only reason that Intel adopted the USB-C connector for Thunderbolt 3 was so that they could sell their TB3 controllers as the 'go-to' USB 3.1 controller, too... because I
want my super-fast external storage array to be plugged into a scratty little connector, designed for phones, that falls out if you give it a hard stare.
Oh, and a USB-C cable killed my brother, stole my wife, traumatised my pet cat and made me go bald. Every USB-C connector is made by strangling a baby seal with dolphin entrails....

But seriously, folks - its a different shaped connector for a bunch of established protocols that work just fine with the old connectors. It doesn't do anything new.