Can't say why they did it but I've had varied results working from home over the last couple of years. As Chris McG stated before, I've also been far more productive when working from home in terms of flexibility (ie. starting early and finish late and then jump back on after the little'n is in bed) and being able to crack on with work without the distractions you get in the office.
The downsides I found were trying to get a hold of people when you need them. If you're in the office you can see if a person is there at their desk or busy in a meeting. I've often found myself ringing 3-4 different people to find out if a particular person is available cos I can't get a hold of them, or indeed the 2-3 people I try. What I have also found is the reluctance for people to ring you if you're working from home. I've had some people actually think I was on holiday/unavailable that day just because I wasn't in the office. I suppose that last point is an issue about communication......
Skype etc is great for meetings but rubbish for impromptu design sessions or meetings where people scribble a load of diagrams on the whiteboards. This is difficult sometimes to add input into.
All in all I like a mix. I couldn't work from home 5days a week, I'd miss the office banter etc but certainly it has worked for me previously.
Doesn't answer ur question though John