ROS (1/2) is just damn handy. There's a plethora of libraries available: navigation, localization, perception, motion planning, visualisation, record and replay events for debugging, high-level behavior definition with state machines and behavior trees, motion control, sensors, orchestration anything you need in a robotics system.<p>I've seen various half-assed versions or something akin to ROS (IPC to have process isolation and distributed, with some processes running on a RTOS) seen built over the years. All of which sucked in different ways. Especially a tool like RViz is always missing.
And in many many robotics video I see (of a moderately complex robot), there's ROS's RViz on some screen.