I know why the state file exist, sorry; I really meant: The purpose of making the state file mandatory. In particular, it makes first-time setup incredibly onerous. You almost _never_ start with a clean slate.
It's great that you're working on fixing that, but it looks like it will be some time before it's quite there, given the seemingly slow pace of development.
It's nice that Terraform can support untaggable resources, but I don't understand why that's the general case and not a special case. I can't remember an AWS resource that isn't nameable or taggable.