I believe actions are usable as part of node composition. I’ve created an example here:
Although, I’ll admit that there is some refactoring that can be done to make things more user-friendly. For example, ros2/rclcpp#635.
Regarding “simple” actions, I don’t think it is very difficult for a user to achieve the desired behaviour with the current implementation (see rclpy “single goal” example). I can see the benefit of wrapping the boiler-plate code into convenient classes for “simple” actions, but I don’t think it is a high priority.
I agree with @kyrofa that tutorials would be a good thing to have for Dashing. I’ve recently created a ticket on GitHub to discuss ideas and track progress.