Pre terraform it would take a half day to setup I new account, create buckets meeting our policies, replicate to backup buckets, etc etc. with terraform we could do same in thirty minutes so we could service many more development teams with same head count.

This work made it easier to keep terraform in sync with aws and so maintenance (e.g. adding a new policy to existing S3 buckets was just edit the S3 bucket module and re-applying to every account. The parser was way easier than manually editing the files manually (especially since I had so much terraform as a test bed of data).