Tier does set up and manage your stripe account based on your pricing.json config, but we go further than that with metering, feature flag style entitlement checks, and other things we plan to provide that you couldn't do as just a provider.
Now, I don't really know the Stripe API besides a quick skim a few years ago, but I think that it's a fully reasonable comment and expectation that when someone says "Terraform for random API" one expects a terraform provider for that.
1. the generated HCL contains plain text passwords if you use any sort of secrets access inside of cdktf
2. because you can use any programming language for cdktf, every project will look different. But then again terragrunt and terraform also have a bunch of differences.