Why Button.on_click() was deprecated?

[mattpap]

Currently I get:

BokehDeprecationWarning: on_click(handler) was deprecated in Bokeh 3.0.0 and will be removed, use on_event("button_click", handler) instead.

This change seems to me counter productive. I also noticed that on_click() is used a lot, at least in submitted bug reports (as I've been testing dozens of issues for PR #11915).

[bryevdv]

I don't recall but I'm not opposed to removing true deprecation since dask uses it.

[bryevdv]

@mattpap here is the relevant PR, I have not had a chance to dig into the details. There was an underlying concern, and the PR did more than just adding the deprecations, so perhaps just undoing the deprecation parts is fine

• Toggle button emits ButtonClick event #11942

[bryevdv]

Here is a tentative PR to undeprecate: #12372