What others see, though, is that the demand that a designer write a production code is similar to a search for a washing machine with decent cooking features. A combo of both does no good.
Who is right?
What comes in handy?
It's hard to imagine a specialist designing, i.e., a good website - that hasn't a clue how HTML and CSS work.
Without any doubt, a general knowledge on technologies used in development of products and interactive services is valuable. A comprehension of the assets, peculiarities and limitations of a given technology helps to make a sound design decision, predict part of the problems, and to evade them.
So no wonder that the former programmers find their feet in UX industry.
And, what's more, a practical skill to use a code might be useful in everyday work, e.g., when quickly remaking a prototype or during preparation of A/B tests.
At last, the knowledge is an excellent communication tool. I've observed that the teams of developers prefer to work with those who grasp their responsibilities. In this way, they share a feeling that their point of view is taken into account and better understood. Anyway, it's hardly surprising. The lack of knowledge can lead to a situation described below.
Is it worth to run after two hares, and develop both in designing and coding? I don't think so.
I get the impression that an UX specialist and a developer in one person is most often searched for by the teams that don't treat the user experience issues seriously, or simply want to economize. Because if we can hire one employee, why should we think of two?
It's often a dead-end, though.
The longer I work in UX, the more knowledge to acquire I discover. Mastery of everything isn't possible, even with devotion of our full professional time, and a part of our weekends.
It's similar to programming. If we want to excel in it, a continuous work is unavoidable. And if we distribute our time for several areas of development at once, it will be considerably more difficult to achieve a high level even in one of the chosen fields.
I don't claim the designers with great coding skills don't exist. They are a rarity, though. It is no coincidence that they're considered as unicorns. It's a fat chance to meet both - these employees and mythical creatures.
Moreover, a designer should - to some extent - stand in opposition to an engineer's approach. Otherwise, what prevails is a tendency to system-centered thinking, focused on technical issues, not a user's perspective. My experience attests that an excessive focus on technology - which is a genuine approach of the designers who code - might limit the design works and negatively impact the end result.
To code, or not to code?
A technical knowledge and coding skills might be of use for User Experience specialist, improve the work efficiency and the communication in a team.
But a requirement to write a production code is a different story. A combination of both: designer's and programmer's roles is not only superfluous but sometimes also detrimental.
As any other additional skill, coding can be your asset. Anyway, do not sidetrack too much from your main course. Otherwise, you may be knowledgeable in many fields - but not really good at anything.