The RMB could have had 3 USB-C ports from the outset, could have had USB and SD too. But it didn't. Why?
Because Apple made the strategic decision that the RMB is a different kind of notebook, one that embraces the cloud, eschews legacy ports, and will sacrifice anything to reduce size and weight. It has a slow, old processor because fans are thick and heavy. It has a blurry, SD webcam because HD versions are thick. It has a newly designed keyboard to reduce height. It has fantastic new speakers making a big sound in an impossibly small space. It has a new plateaued battery design to reduce thickness. It has a single USB-C port because HDMI, SD, USB, VGA, and all the rest add thickness, weight, and negatively impact battery life.
There is little doubt Apple is targeting this device to define a new paradigm in portability.
That said, I do not personally believe, nor are there any indications for me to believe, that Apple will sacrifice anything to reduce size/weight or increase battery life. In fact it's quite the contrary, Apple chose to:
- Use a higher resolution screen that consumes more power than lower res options
- Employ an active touchpad that consumes more power, adds more weight, and saves no cubic volume, when compared to other available mechanical options
- Use two (stereo) speakers that consume more volume, contrary to the original MBA
- Not eschew the headphone jack, consuming more volume and weight when they could have just included usb-c/Bluetooth headphones
- Include a mechanical keyboard when a membrane keyboard would have saved weight and thickness
- Use aluminum for the chassis instead of magnesium or a metal matrix composite
- Etc, etc, etc
Because Apple made the strategic decision that the rMB is an evolutionary step toward maximum portability with the minimum viable features as dictated by market pressures for that particular segment.
IMO, they did not exclude a second USB port, to make a statement, anymore than they excluded a second speaker from the original MBA, to make a statement. It was a balance between goals and practical execution.
If and when they can include additional features to maintain or improve their market advantage, they will likely adjust in a value prioritized manner. There is no reason for Apple to not include a second USB port, should they have the necessary advancements in technology/manufacturing. I, for one, think the market would respond well to a second USB port that did not force a step back in size/weight/battery life.
The single USB-C port in this unique notebook is the sole connection to the past for Apple. And it occupies the space that would have otherwise been used by a power supply, so it's taking up no incremental space in the process. Instead of looking to Apple to add a second USB-C port, you should be thinking about what else they might remove, to reduce weight and thickness. That's the mission of the RMB. Apple didn't release this last year to watch it get thicker and heavier over time. It's going to get thinner and lighter. That's its mission.
I have already considered this, please see the list above.