If I remember correctly Microsoft did a bunch of studies back in the day and found the Calibri had some of the best readability across a range of visibility and reading impairments (like dyslexia).

Serif fonts have some readability features of their own, specifically for printed word.

You are correct. Microsoft invested significantly to create a modern properly designed font that is easy to read on a variety of screens, prints clearly and consistently, scales well, and can do italics, bold, etc well.

I think this came out back with Office 2007 or something. I believe Aptos is actually the new next generation font that should generally be considered an enhancement to Calibri.

While Microsoft isnt great at many things, their investment in font design and support is outstanding.