Agreed, not so nice to return output from action (note that following that idea we'd need to remove/deprecate usage of the action output implemented in the core), but using bare ajax/view PH does not seem to be alternative due to security of automatically exposing and calling unknown views. We'd need to implement new thing, ajax/widget maybe.

I think @ewinslow was original author of this output from action by XHR thing, would be nice to know his opinion.