It would be nicer to most users to have the diagram view enabled by default.

I have the feeling that this feature has been tested by many of us (e.g. when teaching) and we did not run into big problems so maybe it's time to make it the default behavior for the next version.

It's easy to set set_config(display='text') at the beginning of a notebook to revert back to the previous behavior if needed, for instance, if organization have notebooks under CI and they use the text output for quality insurance check.

Note the example introduced in #18758 would need to be updated.

/cc @scikit-learn/core-devs