User blog comment:MisterWoodhouse/The Unified Community Platform Editor and our first release date/@comment-34769545-20200309175404/@comment-24006128-20200309175651

The modal editor goes wide to give you more focus on the content you're creating, rather than the extra stuff.

The pages themselves will remain at their current width in Phase 1. With Phase 2, we'll be introducing new wiki experiences, including changing to page layout. The details are still being determined, as Phase 2 is in pre-production. The desire for fuller width pages is a piece of feedback we've heard loud and clear.