...but because there's only one USB-C port, and current implementations of USB-C need to assign all 4 high-speed lanes to DisplayPort in order to drive a 4k display at 60Hz, you can't do that and use a 5Gbps USB 3 device at the same time - a restriction that arises
only because of the single port design: on the MBA the display and USB are independent.
No. You can't plug a thunderbolt 3 peripheral into a USB-C/3.1 port that isn't thunderbolt enabled. Well, you can but it won't work. Now, maybe you have a dual USB-3/Thunderbolt peripheral that has a USB-C/3.1 port as well (
like this - or
here's another but note the totally separate USB-C/3.1 and Thunderbolt 3 connections in both cases...) - that seems "common" on hard drives (not that there's much choice yet) but your TB3 dock or TB3 display or TB3-to-TB2 adapter just. won't. work.
Also note that both of those drives come with a USB-C to USB-A cable, and so will work happily on a MBA with the same 5Gbps USB 3 connection.
Only with a USB-C monitor (tiny choice at the moment c.f. DisplayPort) or a multiport adapter. Now, don't get me wrong, the
ability to charge via a standard USB-C port using a hub, display or third-party adapter is cool. The problem with the rMB is that there's only one port, so unless you're a proud member of the "I don't need no stinkin' peripherals" club you
need a hub/display/multiport.
Sorry? Who said anything about carrying around a "large external display"? The point is that if you do most of your serious day-to-day work on an external display, then the MBA screen is perfectly adequate for checking your email, running a powerpoint etc. on the occasions that you do use it on the road. However, with the rMB, many people
will need that multiport adapter with them, lest they want to read a USB stick or suchlike (oh, and with the one you linked to, will
still need a separate VGA adapter - what the world still uses to connect to data projectors).
Logic tip "X is not better than Y" does not mean "Y is better than X". As I've said, they're in the same ballpark, in a market where raw speed is not a big issue.
It's not "forward looking" - it is "head in the clouds" from the "grudgingly admit that some people still need more than an iPad" brigade.
- All existing peripherals have what you want to dismiss as "legacy" connections.
- The vast majority of peripherals now being sold new still have "legacy" connections.
- Most of the new peripherals that do have USB-C are backward-compatible with USB-A and (if not sold by Apple) even come with a USB-A cable/adapter (plus, all those double-ended USB-C/USB-A sticks) and will work just as well that way.
- The few/more expensive peripherals that do take advantage of 10Gbps USB3.1 gen 2 or Thunderbolt aren't supported by the gimped USB-C/3.1gen1-only port on the rMB.
- The rMB's one trick is the one-cable data, display and charge docking thing - trouble is, by only giving it one port, Apple have made some sort of dock essential for many people, rather than an optional luxury. Oh, and that's still crippled by the limited bandwidth of the rMB's USB-C port.
Option A: get a computer with a single gimped USB-C and need hubs/adapters for
everything
Option B: get a computer with 2xUSB-A + SD card + Thunderbolt/DisplayPort and - if and when you get a new USB-C device -
use the adapter that came with the new device.
On the MBPs, with 2 or 4 ports supporting TB3, 10Gbps USB and the grunt to drive two 5k displays, then USB-A vs. USB-C is a
debate. On the rMB, its a no-brainer.
Of course, if you really don't need non-wireless external devices in your workflow and/or are carrying your computer around all day, then the rMB is ideal. What it isn't is a replacement for the versatile, entry-level MacBook Air.
(If you remember the very first MacBook Air, it was very much in the same vein as the rMB. That changed)
No, the true Air replacement is the non-TB MacBook Pro - and that is
far too expensive and
still a couple of ports short of a picnic.