I can't answer "why terraform was created" because I wasn't there. Also I only recently started working with it, so by far no expert on the matter. People who don't know terraform often praise it for its platform-agnostic language, but there's an important caveat: the language is platform agnostic, not the templates one writes as they are riddled with platform-specific nouns. You can't take an Azure template and deploy it on AWS.

Having said that, I (so far) like terraform for the same reason you noted: it's more readable and there is great tooling around it. I like state management and the ability to invoke lower-level components (as the shell breakout in your example) when you really have to.

edit: > the declarative style, where you only describe the wanted state, not the steps you take to achieve that state

That is a good and useful thing. It's called "desired configuration management", Ansible works the same way. When the underlying tool works well, it decides on its own how to implement what you want. If you ever watch terraform deploy a complex (10+ dissimilar resources) infrastructure it comes close to magic how it discovers what already has been done and what still needs to be done and in which order.