Update Sep 22, 2021
My name is Rutger and I am the Product Lead for Atlassian’s UI platform.
Let me start by thanking everyone who has voted and commented on this ticket. You have nailed the why we should do this, sometimes with great passion or sense of humor. With your help, this suggestion has become our top-voted request on jira.atlassian.com over the past two years!
That’s why we are currently planning the work required to bring theming to the Atlassian Design System and developer ecosystem, through design tokens. Those will be our first steps towards shipping a dark theme for Jira Cloud. I will give updates here when we have milestones to share, and you can expect at least a quarterly update.
Thanks again all!