Lots of thoughts on this, not sure where to start.

Generally, if you try to reduce socializing, you're seen as antisocial. Trying to be more efficient for the "bottom line" or "good of the company" or whatever makes you sound like a brown-noser.

Yes, everyone gets interrupted. It affects some classes of workers more than others. Not that developers should be treated as "special", but most places I've worked at, mgt and financial people get private offices so they're "not interrupted", but somehow developers building the software the company runs on and/or sells are supposed to be fine in open-air bullpens, just like call-center workers.

There's an element of status I suppose to, but perhaps those with private offices should try to get their work done out in open-air offices for a few months.

Because managers don't understand the "maker's schedule":

http://www.paulgraham.com/makersschedule.html

Developers have to have a lot more in working memory than many other types of position.

Though the better you get at organizing your code, the less you need to push your working memory. In the first decade of my coding life, it took me a while to 'warm up' and 'cool down', distractions were extremely irritating. In the second decade I started to find it easier to jump in and out of the coding state, by maintaining a more focused problem-space.

I am of a similar age to you I am guessing. I think many people have a mythical view of their own ability to escape the typical human experience.

Perhaps distractions don't damage your productivity, but I am guessing you're merely more productive now, so the short bursts you make are more productive than your old longer bursts, therefore your 'Warm up and cool down' periods FEEL shorter. It's not like people do nothing when not in flow, they just do less.