I like ROS, the library of things you can use to get prototypes running quick is nice, but wish they hadn't rolled its own build system in addition CMake (Catkin) with the concept of packages, while not being a true package manager. Whenever your middleware dictates your build system things start to get pretty messy. My dream for ROS 2 (or maybe 3) is one where ROS does less instead of more - sometimes simpler is better.