Just a little detail about the Wordpress-update-vs-trash example.
I'm pretty sure I have read on different places that, on a website, a button should be used for something likely to actually do something while a link should be used only to move the user to another webpage. In few words, links should be side-effect-free (go to see an article,, open a new tab or a new window, etc) and for every action that changes the state of the model (post something, delete another thing, send a third thing, save a fourth one, etc), a button must be used. I think that makes sense even though that usage is not respected everywhere.
Then, the usage of a link here seems pretty bad but in the same time, it has the "convenience" to be harder to click than a button. Finally, what should be used ?
Nice article (as usually) though. Congratulations and keep on writing.
(sorry for my language btw)