The 2.5 5400rpm Laptop HDD was a big mistake, especially since the console inside has room to fit two 3.5 HDDs, it is giant in there, why didn't they put the power brick in there and a 3.5 drive? Don't get it, especially since the heat goes directly out the top. Currently the Xbox One has to run 3 operating systems, do background tasks like GameDVR and run your game, a standard Laptop drive will have about 60Mbps of bandwidth, it just isn't enough.
A USB 3.0 3.5 7200rpm HDD will have the bandwidth of around 180Mbps, it is nearly as fast as a cheap SSD every one seems to buy, like seriously though cheap drives, benchmark them, you'll only get 200-300Mbps, not the 500 as advertised, even slower for small files. We'd be able to load games faster, have the Operating system auto optimize itself for full bandwidth use of the internal HDD and GameDVR would be able to use more than 4MBps for the bitrate.
Seriously I hope if External Drive support comes, Microsoft are smart enough to allow us to have 50Mbps 1080p Video like you can get from the H.264 encoding that is built into the hardware of an Nvidia and AMD card.. I really hope something that that is support on the chip built for the Xbox One.
Just needs this support desperately, I have no idea why they didn't just make a removable HDD like the Xbox 360 slim, it isn't like anything is stopping it. At the very least though give us the external drive support.