This is effectively the 'dry-run' feature that has been sought for a long long time [1], and led me to switch to Terraform (which does do this amongst other key differences) . Why did it take so damn long to implement?

I do appreciate it has come about eventually. Terraform has its foibles (and stupid half-declarative language) but it would take further improvements to consider going back to CF.

[1] https://forums.aws.amazon.com/thread.jspa?messageID=563929&#...