Restore manual configuration for Sonos, Cast, and Nest

I’ve raised an issue on Github regarding manual configuration not working for Sonos and Cast in version 0.7x.

Apparently this is a “feature” and according to the 0.72 blog:

Another change is that Nest, Sonos and Cast will now have to be configured using a config entry. Config entries can be created via the integrations page in the config panel. This is a concept that we have been developing for a couple of months now and it’s our goal to eventually use this as the way to configure all components.

Is there a technical reason why manual configuration in configuration.yaml is going away and is it possible to enable it along with the integrations tool?