
Good communications is essential
If you want to be long term successful, anyway.
Contrary to some comments, this doesn't mean you studied Chaucer or necessarily the classics (although that doesn't hurt).
I have had to effectively communicate with people at all levels of organisations and the interesting thing is that they all effectively speak different languages, even though (in most cases) it has been English.
It isn't just about fixing problems quickly, either. Can you explain how the problem occurred so it can be prevented in the future? In my experience, being able to clearly explain what a problem was / is and how to prevent it is a very important skill.
Senior management wants to know there is a solution. Engineering management wants to know the solution and how it might be implemented. Engineers want to understand the solution and the practical effect.
QA wants to know how this will be documented and applied.
If you have junior engineers who you are mentoring (you really should be) then it is perfectly possible you will need to be able to explain a concept in at least two different ways.
If you are helping with bid work then you need to be able to explain how your part of the bid will solve the customer's problem.
As far as getting jobs goes, the fact I really know my core subjects (and a lot of tangential ones) would not be very useful if I cannot explain clearly how and why I know those things.
The list goes on but that is the gist of the subject. Explaining how a fix affects the business to a senior manager is a lot different to explaining how that will affect day to day engineering to the line manager.