Objectively there have been an absolutely enormous number of "improvements" to MS office (including Outlook and Word) over the last decade. The biggest is probably cloud/simultaneous editing capabilities. See https://www.microsoft.com/en-us/microsoft-365-life-hacks/sto... .
Interestingly, there is a decreased emphasis on the file format- the opposite of your point. In addition to cloudy used on mobile devices, sharepoint, etc; since 2007 or so Word has used docx, which has better cross compatibility with other suites, even Google Docs: https://www.howtogeek.com/304622/what-is-a-.docx-file-and-ho... .
My personal use patterns- I use LibreOffice quite a bit, Google Docs rarely, and MS Office daily for work. Outlook and Word have changed a lot and continue to evolve (watch for copilot integrations).