Well it would take considerably more time as you you have to clone all the partitions correctly first. Also without any ESD protection you risk latent damage to the internals.
I get it, I have a day one box too, but I can't see my external HDD sitting behind my box so it doesn't bother me. I would just add another for how cheap they are if I needed it.
Looking over the directions, you don't have to touch the CPU heat sink or anything else, every part is just a unplug and plug back in. Nothing that could really get damaged that could cause major problems with the system, if you are reasonably carful. That is the easy part, doing the software to clone the drive is a little longer of a process.
Yea, the other side, if your doing an External, you can get like a 5-6tb drive for under $150-200 (I scored a 5tb 7200rpm USB 3.0 drive for $147 to use on my HTPC). With 1tb and if your a hard core gamer, you will run out of space at some point. 5tb, you need to be pretty diehard or after about 4-5 years of downloading the free games each month to run out of space.
As I am long out of warranty now, I am tempted as a 2tb 2.5" drive could be had for under $120 or so. It wont last forever but, it sure will extend the life of the xbox one with out any external boxes..
I just wish 4-5tb options in a 2.5" drive was an option or at least an affordable option (largest 2.5 drive is 2tb) and it would be a no brainer for me.