"So you've got a tablet but you feel the need to add a keyboard and a pointing device - shouldn't you have just bought a laptop?"
No - I use the keyboard occasionally*, and the mouse even less frequently.
The excess mass and short battery life of a laptop, combined with the weaker screen and reduced connectivity mean that for the vast majority of the time it's not the right option for me. Particularly given the cost of the device, compared with that of a conventional laptop.
In the last 2-3 years of tablet usage I've used a mouse a few times (one Win95 era game played via DOSbox) and wanted for one exactly once, providing family support via teamviewer, and in that instance I could simply talk them around the screen - the video feed was far more important than the control aspect.
Outside of work I rarely use a PC any more, almost all of my personal server maintenance is command line based, and the tablet does that just fine. Frankly if it weren't for security restrictions at work I could do my day job (mostly SSH, scripting rather than coding, and web interface access to the software I support) on a tablet quite happily as well (probably more happily than the current PC based solution). I might want two actually, but that's just to replicate the multi display layout I have at the moment.
I can see that people who have Windows Servers to maintain would like to use a highly portable, long battery life, decent screen device to connect to them, and a mouse then becomes rather useful. Anything that allows niche functionality to be extended by the use of an appropriate accessory has to be a good thing.
I can also see that companies with thin client infrastructures would appreciate the flexibility allowed by having I/O devices for tablets. BYOD, connect to the citrix server and we retain control over the main work environment...
For the *vast* majority of users a PC is overkill nowadays - I've not looked at how well Microsoft support VBA macros between devices, but even that is a fairly small section of users - and it might be that all that is handled rather differently in the cloudy versions of office (maybe, no idea)
* Yes I know I had to have planned to use it, but even when I take the keyboard with me "on the off chance" I've not had to use it. The on screen keyboard works well enough for emergency fixes, the BT keyboard is more useful for extended sessions.