Sure you can run a windows 8.1 tablet as desktop. I got the
Asus Transformer for the wife. She wanted a small thing for travel and she only uses very simple applications.
Her laptop in Germany died and if I cannot get it repaired (probably the mobo), I will hook the Transformer to a 19" TV that I have in the basement. We already have a
Motorola Bluetooth Keyboard with trackpad and a bluetooth HP mouse. Then she should be all set.
The quad Atom CPU is amazingly fast and for storage we use a 32GB MicroSD card plus an external SSD in a USB3 enclosure that I had also been lying around. That is a fast combo on the Transformer's USB3 port. We use it mainly for images.
Could you have done all that with an ipad or android tablet?
I know nothing about iPad, but I do have an Android Nexus 7 tablet with which I could do the same setup. It has an HDMI port, my Bluetooth keyboard and mouse work on it and with the OTG cable I can attach external devices.
But I never thought of doing that because that tablet is setup for on the go. I use it for navigation, trip planning, free phone calls (even from Europe to the US), webradio and web TV, an occasional check of my mail plus a lot of fun applications that are of the 'consumption' type or at best simple things like the wife plays Sudoku on it. E.g. when I am bored, I listen to the airport traffic control at airports around the world.
I do have a complete office package which I bought from the Playstore for $6 - I was just curious what that is - it is pretty good. But a tablet does not lend itself to that kind of work. Maybe drafting a letter is OK, but an Excel type application I would not venture to make.