When I was very young (Grade 1 to Grade 5 or so), my parents had a rule that I had to do my homework on the kitchen table. I hated it. I remember sitting there with my math homework, tears running down my face, my mother telling me not to carry on and reminding me that "smart kids finish their homework."
From Grade 6 until about six weeks ago, I had my own desk. The furniture changed. First it was the fold-down in my parents' old bookshelf. Then the pine scrollwork desk with the useless pigeon holes, my aunt's old kitchen table, my uncle's old clear-top with the National Geographic map of the world under the laminate, then the IKEA desk I just got rid of.
Some were good desks (the IKEA was my favourite, hands-down, which is probably why I held onto it so long). Some were bad — the pine one wins for that, since it was originally a hall desk design that was made deeper and wider to be sat at, yet still didn't work.
For my new apartment, I got rid of the IKEA desk (too much horizontal space taken up), and replaced it with a narrow shelving unit that has drawers. I haven't missed a desk yet.
The truth is, I've never really got the hang of sitting at a desk. Maybe it's because I associate it with being uncomfortable. Maybe it's because it's something I do away from home (ie: school or work). Maybe I just like sitting on beds and couches better.
In university, I had a desk, but I would only use it for the final typing-up of my essays (it being where the old Roland 286 I had resided). Otherwise, I used the living room couch to work on. I also marked papers on the couch when I was a teacher, and once I got my first laptop... that was the end. The laptop I'm writing this on now stays in the living room when it's not on the road, and can be found tucked under a piece of furniture when I'm not using it.
As far as my fiction-writing goes, I think the only time I work at a desk is when I'm adding a couple of paragraphs to a short story during my lunch hour (using the N-800, not my work computer, in case any co-workers read this!). The vast majority of last year's NaNoWriMo got completed either in the comfy chairs at home or the comfy chairs at the nearest Starbucks.
This, of course, is heresy. Think of all the writers' biographies you've read. Now think of how many included a description of their desks. Alice Sheldon had three, one for each name she wrote under. Ernest Hemingway had one that was to be stood at; he had back problems and couldn't sit for long. Big desks, small desks, desks in "dens" the size of my apartment, desks tucked away to one side that only came out once the children were asleep. To write is to be a desk owner.
But memory, even the collective sort, is selective and fickle. Did Jane Austen have a desk? From what I've read, she rarely wrote at one, working instead in the parlour with the rest of her family as company. And Hemingway is more famous for his use of Moleskine notebooks than for his specially-designed desk.
Desks will always be useful to someone, somewhere. But the wisdom of their necessity as writing equipment needs to be questioned.