Original iBook only had one USB port
And a headphone jack that could output composite video.
This new MacBook looks evolutionary; hi-res display, entirely new touch interaction option, super-thin but usable keyboard and fanless, so no moving parts.
Just like the iMac and iBook kick-started Type 1 USB the third party peripheral market, this MacBook will probably do the same for the far more capable USB-C connector.
Want more ports? Buy a MacBook Pro - the 13" retina is $100 cheaper too