I'd love to hear your suggestions for changes we could make while keeping it somewhat WSGI-compatible. It took a few years to refine it to where it is now, so it's not like we just threw something at the wall.
There's the problem. WSGI is fundamentally flawed too - it could also be using generators for a two-way communication channel instead of stringly typed callbacks.
In a world where Python has optional static type hints, it would be nice to have concrete objects passed too.