OK, I get that I am extremely ridiculous, but I vaguely remembered a presentation I saw 12 years ago, and single-stepped frames through a bit under halfway through that video to check Microsoft's actual measured internal stats on this exact question https://twitter.com/AlanMCole/status/1298641971750240257

MS actually measured the number of times people clicked (not just Ctrl+Ved) on Paste-with-formatting vs Paste-Special in Office 2003 in a random week in 2007. And they collected all of that data into an absolutely enormous Excel spreadsheet that they used for driving UI decisions

They didn't just collect that, of course, they also collected a zillion other metrics, all for optimizing their UI (and that's how Office 2007 happened)

And when I say a lot of data, I mean a *lot* of data (this was in 2008)

Anyway, halfway through the presentation they show off their mega spreadsheet of most used commands in the major Office apps for a random sample week sometime in 2007 and scroll through it super quickly. But if you're sneaky you can peek at the data as it zooms on by.

And so anyway the winner, by fully a factor of 15 is people prefer pasting with formatting.

So there you go.

That's why the default is paste with formatting.

Bonus trivia: roughly 50% of people pasting do so via the button, not via Ctrl+V. Which is why the paste button in Office apps is so big. It's because people click it lots.