Agreed that Sony should add external USB support for games at some point, but at least internal hdd is already upgradeable and USB can be used for exporting screenshots and the like.
Not sure how many PS4 owners are reading this thread, but just FYI the 2TB 9.5mm Samsung Spinpoint M9T hard drive (available by gutting a seagate 2tb backup plus slim drive bought from Amazon) now works flawlessly as internal in all PS4s as of the 1.70 update. 1766GB free for use after formatting/system init according to the System Storage Management screen. Highly recommended, just be warned that it will take a _very_ long time to redownload all your stuff.