In point of fact, Isaac Newton did not "explain just gravity" - he also invented the calculus and developed important insights into the nature of light, among numerous other contributions to science.

During the same life (presumably as indivisible to him as mine seems to me - but that's another issue), he apparently wrote more on aspects of religiosity than he did on science (according to a lazy skim through the wikipedia entry), dabbled extensively in alchemical investigations, ran the Royal Mint (and as such was in fact deeply concerned with the "role of money in society" - to significant practical effect at the time), and became an MP.

Of course, this might not impact upon the point you are trying to make - you might just have selected a poor example.

However, casting about for a better example (immediately recognisable names who have made a singular contribution to science but did nothing else of note/had no significant, tangential side interests) - I find it hard to come up with one. Even if there is one, I think that s/he might well be an exception, rather than a rule.

So what's my point?

I feel that your defence of narrowness is too narrow, and that your denunciation of "everything is connected" is too broad.

Everything is indeed connected - this is trivially true; philosophically, logically and physically. As you say, though, the statement only becomes interesting when we start to examine what the connections are; how they function, what the relationship of different connections is, what networks these connections form which can be recognised as recurring patterns that have real effects/can be affected.

In the context of these investigations, narrowness is just a question of perspective, and any notion that operating only at particular level of perspective is 'correct' seems fatuous. Even the suggestion that one level of perspective is generally to be preferred would need careful justification.

In a current, 'real-world' context, consider the designer of a functional aspect of, say, a transport system. We expect the designer to produce something efficient, safe, economical, and practical. We might say; that's it - you have no other responsibility. But each of those requirements can be viewed more or less narrowly.

For the last three hundred years or so, western culture has been tending to suggest to people that they should view the requirements of their task more and more narrowly. And this has appeared to be highly 'successful' - in terms of valuable and significant parameters such as mortality, increasing education, enlarged franchise, standard of living etc. - so that the trend becomes reinforced.

However, it has become evident that this narrowness has led us to ignore the wider network within which we live - the ecosystem of the planet. Our transport designer should no longer consider environmental impacts as 'externalities' that can only distract from the task at hand.

It is becoming incumbent upon us to develop a range of perspectives, and to understand the usefulness and application of them, and how to change perspective while working on a single task. This is hard for an individual. For it to become a cultural mode is monumental.

Narrowness is an effective mode of operation only when it is appropriate. Opening our eyes wide and jumping into a sea of possible connections without prejudging them is another viable mode in appropriate circumstances.

As an architect, I find I need to employ a range of modes, from extreme breadth to extreme narrowness. One metric of an effective architect might well be to look at how well s/he judges what level of breadth/narrowness is appropriate in a given situation.