New outlook is less functional but much better UI design (it's just outlook web access after all). Outlook hasn't changed in forever because so many corporate high ups use it and think they know how it works. They always respond to emails that are already answered because they didn't see the newer reply in their inbox. I suspect this resistance is why it's a totally separate program to the old outlook. Yes, there are settings to group threads in outlook, but the interface is still pretty unintuitive and the vast majority of these users don't change their default settings anyway. In my experience the terrible defaults create more problems than outlook solves. And the server syncing can be really slow at times. Personally, I'm very happy that MS is finally showing some interest to modernize outlook, the more people who use it the easier my job will get.

Also ya the name is stupid. Teams (New) gets me the most. Idk who possibly thought this naming scheme was a good idea.