Exactly. Yes, it would be nice to have 10 ports for EVERYTHING, but giving the applications that this machine is built for, it doesn't make sense to add them. Portability is its game, and if you are a power user that need everything and the kitchen sink, there's the the rMBP available.This is the logical device for the anti-tablet crowd (hi).
This is a nightstand computer, a coffee shop computer. An email, youtube, browsing computer. It's not for CAD renderings and editing movies. If you want to attach a bunch of accessories, this isn't that computer. The concept is ease of use portability, which doesn't entail dragging along your mouse and external hard drives and all your other gadgets. That's not what's going on here.
Amazing how people are fine with no ports on an ipad, but give a slim notebook the same treatment and everyone loses their minds.
I really think people overestimate how much they need external appliances these days, when everything can happen online or wirelessly.