I know there is a post about this, but it was from 2015 and I think it's time to refresh it seeing this feature is becoming more popular among Android's apps.
I believe it would be an amazing idea to implement a dark mode into Strava for Android. Mainly for 2 big reasons. The first reason is, it can improve visability if you need to look at it during riding (And it's easy on the eyes). And secondly, dark mode generally reduces battery life. This would be a huge feature for people who mount their phone to their bikes and keep the screen on. It's 2017, and a lot of apps are coming with dark mode. Everybody loves dark mode, and if not.. they can disable it.