I don't understand why any of these changes have to happen in the first place. "The updated Outlook for Windows experience is simpler and more customizable so you can work faster and get back to the things that matter most." The UI updates as of April 2019 amount to very little. We upgraded (?) to office 365 from 2010 at the turn of the year and have been amazed at how Microsoft has ruined outlook in particular. All microsoft has ever needed to do was look at Outlook 2010 for PC and build from there with behind the scenes upgrades and improvements. The ridiculously huge message header size ,the not quite finished look of the calendar and the unusable preview window if viewed from the bottom are among many huge mistakes in developing outlook from 2013 forward. I keep hearing about the "modern" look to the UI and it just disgusts me. Why make a "modern" look if you are going to ruin functionality? There are a few things with office 365 overall that are definitely improvements ( ie. xcell opening different files in new windows) which keep me from re installing 2010 for our entire company but I am still on the fence.
The outlook 2010 UI did not need to change much with newer editions. All of the "fixes" Microsoft is doing are just an attempt to respond to sensible users and really get back to what worked and actually make it easier to "work faster and get back to the things that matter most". Some of our company PC's still have office 2010 because those people use outlook extensively and we are not going to make them suffer through the joke of outlook 2016. All users should look at that UI and especially the Microsoft development team to get a better idea of what to do to fix outlook 2016 and future editions. How anyone can think the current version of outlook is anywhere near as good as 2010 and before is a complete mystery to me.
Brian