1. Never mind posturing, it's the posture - I get back and neck pain just thinking of working from a couch or floor :(
2. I like my multiple 27" monitors. Going back to just a single 14" feels like a huge productivity hit.
3. Same thing with proper keyboard + mouse, vs just a touchpad or even the trackpoint.
So I'll agree that there's a lot of posturing and professional front in this and many professions; but even without that, I've always far far preferred my home office to either proper office, or working from living areas.
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The other aspects are more age dependent (though I believe so is the posture / back pain;). It helps to distinguish "working area" and "non-working area", triply so once you have family. There's a million things that I do better at when I'm "in the zone" - ingested the background, focused on the problem at hand. Distractions reset that counter - I love my kid, I love my wife, but there are aspects of my work that don't benefit from their presence :-). This is probably part of why my personal most productive times tended to be late at night when the world has settled down and distractions are at a minimum...