No, the USB-C on the
macbook is
not "so much faster" than the Air! Can we please put that nonsense to bed?
The USB-C port on the Macbook provides a DisplayPort 1.2 output and
one 5Gbps "USB 3.1
gen 1" port. It doesn't have the new, faster USB 3.1
gen 2 and it doesn't support Thunderbolt.
"USB 3.1 gen 1" is the same 5Gbps protocol as USB3.0 or "SuperSpeed USB".
https://en.wikipedia.org/wiki/USB_3.0
...and a single USB-C port can't even do 5Gbps if you also connect a 4k@60Hz display, since (with DisplayPort 1.2) that needs all four of the high-speed data lanes: (
https://www.vesa.org/news/vesa-brings-displayport-to-new-usb-type-c-connector/) and only leaves capacity for USB2 "non-Superspeed" data (so no 1G ethernet, for a start) (
https://en.wikipedia.org/wiki/DisplayPort#USB_Type-C).
The MacBook Air has
two 5Gbps USB3 ports
and a SD card reader
and a separate DisplayPort 1.2 output which
also doubles as a 20Gbps Thunderbolt 2 port.
The Air has
significantly more i/o capability than the rMB. What the rMB offers is a party trick of one-cable docking
with charging - provided you don't want to dock with a 4k 60Hz display
and a SuperSpeed USB device at the same time. The Air can happily do
two cable docking with its Thunderbolt port - with far better bandwidth for multiple peripherals - if you can tolerate the ignominy of plugging in the magsafe as well.
Apart from the single-cable charging thing (which the MacBook
forces on you because it doesn't have a separate charge port) there is nothing that the rMB can connect to that the Air shouldn't be able to connect to
and drive at 5Gbps. New USB-C external drives often come with the required USB-A adapter in the box, half of USB-C pen-drives are double-ended. Even the 4k USB-C displays
ought to work on the Air with a MiniDP-to-USB-C cable (frankly I'm not taking bets on that one - but the VESA spec says that USB-C to DP cables should work both ways). Then there's all the Thunderbolt devices that will work with the Air - even many TB3 devices, with an adapter. And, yeah, at the moment I'd rather need adapters for the USB-C/TB3 devices I don't have yet than all the USB-A devices that I already use day-to-day.
Now, in the case of the MacBook
Pros -
their USB-C ports support USB3.1
gen 2 and Thunderbolt 3, at up to 10Gbps and 40Gbps respectively - and they all have at least two of them - so there's a real future-potential vs. present convenience debate to be had. The rMB, though, with a single port and no gen 2 or TB, is seriously limited in connectivity c.f. an Air.
Cue the First Church of the One True Connector saying this is not true because Chewbacca is a Wookee from Kashyyk but he lives on Endor. If in doubt, go read the specs of actual USB-C products (you may have to look at the small print) and the available in-depth information on USB-C, TB3 (not marketing infographics from intel or the USB-C consortium).
The bit about a USB-C port only being equivalent to a
single USB3.1 port (it only ever uses 2 of the 4 lanes in a USB-C cable) may be news to you if you haven't read about the
forthcoming USB3.2 standard (which can use all 4 lanes for USB - although not at the same time as running a display, of course). The great news is that all of your USB-C cables will work with USB 3.2. The bad news is that your 2017 USB-C computer won't support it...