On Mon, Oct 26, 2015 at 12:43 PM, Pau Giner <pginer@wikimedia.org> wrote:
I think the purpose of colour buttons is to set similar expectations. We highlight the next logical step and indicate whether some new content will be created (green) or destroyed (red) as an outcome. Creating and deleting content, even if these actions can be undone seems worth some considerations in an environment where content is public and edited collaboratively by many.

The create/destroy/other split doesn't match the "dangerousness" of the actions well, though. The typical way for a non-admin user to make a mess is via page move (which usually cannot be reverted without admin rights) and merge-type actions (wikidata item merge, or adding an interwiki link on Wikipedia that causes different concepts to be merged). The most dangerous actions with admin rights are probably user blocking and page history merge. None of those are constructive or destructive in the sense the UI uses those terms.