It's actually a very decent launcher, I used it for a while after Nova screwed the pooch. Have moved on since then, and if I hadn't, I certainly would be leaving over Bing chat.
Customization, more features than the default. For example you can rename apps, change icons of apps, organize your apps to categories etc. Something not possible with the default launchers. Yes, other 3rd party support these, but if you already use some Microsoft products like Onedrive, Outlook etc, Microsoft launcher could be a logical option. They already spy you, so...