Not able to re-deploy an app after its deletion

It's the intended design. It's more like a UI design bug/improvement.

I should also mention that this behavior is only the case for non-snapshot artifacts. Snapshot artifacts are mutable so they dont see this behavior.

This is known, expected behavior, and is because deploying an app through the UI actually deploys the artifact first, then tries to create an application from that artifact. This really requires a redesign of the application creation process in the UI, since it requires being able to create an application from an artifact, which implies some way of listing application classes, the config they support, etc. I don't imagine this would be changed in 3.3.0.

The other option is to change the behavior of the API so that it deletes the existing artifact in this situation, but that causes issues if there are any other apps using the same artifact. Maybe it is ok if you assume people who are deploying apps this way have a 1-to-1 relationship between app and artifact.