My solution is pretty simple, and is a combination of watchOS 2’s glance as well as iOS 10’s new Control Center. Instead of having a Now Playing app on the watch, why not bake those controls into the watch’s Control Center? Swipe up on your watch face currently brings up Control Center, so just add the ability to swipe right on Control Center to bring up media controls.
For some reason I thought this was a feature of watchOS 3, but as it turns out, that’s not the case. Count me in with Matt, though, I hope Apple adds this before the final release. It’s a better implementation than forcing users into their dock and would bringfurther uniformity to iOS and watchOS.