My suggestion is that adding a mini-DSL for parsing nested functions as nested tests is less readable for the average Python programmer who has not seen that plugin before.

And I've never had a problem with reading class names vs. function names; we do that all the time when reading Python code.

I think this is clearly in the realm of subjective preference for what "looks nicer", which I'd call aesthetics.

On the other hand, this probably breaks your IDE's pytest integration, which would be an objective material downside.

Whatever floats your boat though, definitely not a hill I'd die on.