I remember writing with a mechanical typewriter. My mum had one when I was younger and I used to write my dodgy horror movie scripts on it.
None of them have survived to this day (I was only ten or eleven years-old), but what has stayed with me is the sheer unpleasantness of the experience of bashing away on the stiff and unforgiving keys. So, why anyone would want to invent a USB interface for typewriters is beyond me. In fact, I thought that this was all an April Fool’s joke until I saw the amount of websites offering to sell them.
I suppose that these might appeal to the kind of people who see Steampunk as a lifestyle choice, rather than as a literary sub-genre, but otherwise I’m a bit befuddled by the concept.