I remember in years gone by, there was a (Sun?) keyboard with extra keys down the left with names like cut, copy, paste, insert, close and so on. I'm half tempted to buy one of those gaming keyboards with programmable macro keys and map one of them to this "paste as plain text" sequence.
I can see how it's unusable on a laptop, on a full-size PC keyboard that's OK.
> how often do you want the formatting from the source, vs. seamlessly matching the target?
I don't write word documents unless I want rich text features. Just for text there's nothing wrong with plain text or markdown files.
Copy-pasting from visual studio is the easiest way to apply good quality syntax highlighting to a code snippet. The IDE is even smart enough to copy them with dark-on-white colors despite I use dark theme.
Also, I often cut & paste within the same document.
Just for clarification, Paste as Plain Text doesn't paste an unformatted string, it blends with the target formatting. So for example if you are copying a phrase you copied off a web page into a Word doc where the current paragraph is 12pt Georgia, you get 12pt Georgia no matter what the formatting was on the original document. The default Paste will attempt to replicate the color, weight, font size and family of the original web page into your Word doc, which is highly unlikely to fit in with the rest of your document.
Try Control+Alt+V. I have Office professional plus 2016, works here, however it opens a popup. Plain text is at the end of the list, making the complete sequence Control+Alt+V, End, Enter.