An engineer with soft skills, but no hard skills, isn't an engineer – but their soft skills may be usable elsewhere. (I find that engineering managers need to have a decent amount of engineering skill to be at all effective)
An engineer with hard skills, but no soft skills, is somewhere between unproductive and an active menace. The bare minimum soft skill is the ability to work effectively with others in a team. Someone who lacks this skill contributes more negative value, by harming the operation of the rest of the team, than any one person is able to create, no matter how good they are. And a system built by one person in angry isolation (which is where people quickly end up if they lack those skills) is a disaster from other perspectives: for example, production maintenance and operations, where ultimately only one person understands what they've built.
An engineer with enough hard skills to function in a team, but only that, is a net positive, but I'd hesitate to describe them as "solid" – rather, I'd say that gets them to be an effective journeyman, but means they'll never be able to lead anything, even something small.
Conversely, the "engineer" with lots of soft skills but minimal hard skills can be a manager – but not of anything too complex. Again, their career is permanently limited.
So there's a real law of the minimum at play here. But notably, the place you drop to at zero soft skills is way worse than the place you drop to at zero hard skills. The latter, you can find a use for; the former, you need to get out of your organization as quickly as possible, because they do active damage every day.
Sound engineering judgment typically implies a good understanding of the full context of the problem ("is this a good tradeoff?"), which often involves things beyond the merely technical. And without all of the other things you mention, which are definitely in the category normally called "soft skills," the best engineering judgment in the world will go to waste.
No no, not at all! One of the key things a manager needs to do is create a culture of mutual respect within the team, between everyone and everyone else. If the manager doesn't actually respect people, that's going to be a disaster.
This is tied to one of the core categories of soft skills: getting a group of people to work together as a team and trust each other.
On (2) -- I picked a personal anecdote, but I've seen this be very true on much smaller teams, as well. (Including, as it happens, AlphaGo! Think about what went in to creating the circumstances where it could be tested... they did some heroic labor)
On (3) -- not just UX! Interaction with the outside world is a feature of every aspect of how people will use (or misuse) the system.
(5) Totally agree that this is crucial. I did give a few examples (later in the article) but I think that coming up with a good taxonomy of these skills, and patterns for learning and teaching them, is a huge challenge going forward.
Many intuitions are useful: for example, you note that some people want more laughter at work, others don't. A good leader should be able to make that meta-analysis, figure out what the team needs, and create that. But needs to do what? How do we describe the (positive) effects of laughter that you're trying to capture?
An engineer with soft skills, but no hard skills, isn't an engineer – but their soft skills may be usable elsewhere. (I find that engineering managers need to have a decent amount of engineering skill to be at all effective)
An engineer with hard skills, but no soft skills, is somewhere between unproductive and an active menace. The bare minimum soft skill is the ability to work effectively with others in a team. Someone who lacks this skill contributes more negative value, by harming the operation of the rest of the team, than any one person is able to create, no matter how good they are. And a system built by one person in angry isolation (which is where people quickly end up if they lack those skills) is a disaster from other perspectives: for example, production maintenance and operations, where ultimately only one person understands what they've built.
An engineer with enough hard skills to function in a team, but only that, is a net positive, but I'd hesitate to describe them as "solid" – rather, I'd say that gets them to be an effective journeyman, but means they'll never be able to lead anything, even something small.
Conversely, the "engineer" with lots of soft skills but minimal hard skills can be a manager – but not of anything too complex. Again, their career is permanently limited.
So there's a real law of the minimum at play here. But notably, the place you drop to at zero soft skills is way worse than the place you drop to at zero hard skills. The latter, you can find a use for; the former, you need to get out of your organization as quickly as possible, because they do active damage every day.