As you even say yourself, for a task you might do once ever, why would you add a button to clutter the UI? That's like Apple adding a button to the iPhone to indicate that you'd like to terminate service with your carrier. Just wouldn't make any UI sense.
It MUST be common user functionality both for private and corporate users.
People have completely unjustified trust for these cloud-based services when in the face of it, they screw people's data up all the time. You should be able to maintain an offline archive of all of your data to guard against vendor failure.
To be 100% honest, at least here in the EU, I think they should legislate to make sure that a) you can get your data back when you so desire and b) the data should come back in an open format.
And, of couse, when you do realize SP is utterly awful when compared to its competitors, it makes the migration a lot easier.
I can easily imagine a migration from SP a couple years down the road would cost a lot more than the US$250K they are being offered to leave Notes (which is every bit as awful as SP)
I've watched SharePoint go with a spectacularly large boom when some muppet renamed the AD domain... That was a fun two days of my life reverse engineering it believe me. Thank goodness they did write it on top of the CLR as it's easy enough to decompile then to work out what the hell is going on.