Front-end JS? Need, mainly. Most of the UI/UX people I worked with have not maintained their skills, and I was getting tired of knowing more and doing better work than them in their own field. As it happens, there's a much better market for that work than for the back-end and architectural work I've been doing the past couple of decades.

Oil-and-gas? Luck - I live in a city with a lot of head offices. Eventually almost everyone works for one of them :) It was just my turn. But it looks like a long-term gig, which is great.