Yes, it's nice to be able to work in very casual clothes, so casual that you wouldn't wear them out of the house. Yes, it's nice to be able to eat your own food and not have to travel on nasty roads or in rainy weather. Yes, setting your own schedule is very useful.
But there are drawbacks to working at home. The principal one for me is that I feel cut off from the rest of the world, and sometimes don't even leave the house. It's especially tempting to stay in when the weather sucks. Today's weather wasn't really too bad, as long as you weren't planning on traveling anywhere, but seeing snowing falling makes me less likely to venture out, unless it's time to ski or snowshoe. So it was mid-afternoon before I went out to shovel and see what the world was up to.
I also don't work well when I don't have the input and feedback of other people. Perhaps that's why I feel energized and tend to be more productive after I get back from a conference: I'm full of ideas.
And the most likely place for me to find the people to interact with is the coffee shop. Even when I was working downtown, a trip to Ancora was often the most productive part of my day. I'd be trying to reach people all morning - leaving voice mail messages, emailing, and playing telephone tag - and finally say, "I'm headed over to Ancora for a cup." And hour and a half later I'd wander back into the office. While walking the block to the coffee shop, or waiting in line, I'd see most of the people I'd been trying to reach all day.
So here is another reason for the efficiency of urban area: As I mentioned in a previous post, casual encounters are increased, and it is easier to take advantage of these casual encounters, when you are walking and using local shops. If I had worked in a large office building, or had to drive to errands on break, I wouldn't run into people from other employers or offices. Those encounters were what drove both by advocacy work at Bicycle Federation and my alder work. Being able to talk to people without an appointment, without a plan to discuss anything in particular, stokes work creativity.
Obviously, I'm not the first person to notice this, and the link between density and creativity is a familiar theme of Richard Florida, but this is an observation of my own behavior and needs. YMMV