When first introduced, ctrl-c was the TERM signal to exit a program. Microsoft didn't give one rats ass about POSIX conventions at the time—especially in a GUI—so "c" was an easy pneumonic for "copy". "V" just happened to be the character right next to it, so that was paste. (Also because "p" was for "print".)

ctrl-v was pretty basic, because the all the apps were basic. Most text was basically unformatted (Notepad) or moving from one part of a document to another (Word). Then companies introduced the notion of grabbing metadata along with text, so that you didn't have to figure out what font, size, and color were being applied every time. Then copy/paste was applied to non-text like image parts, files in a directory, etc. You could copy graphs from Excel and put them in your PowerPoint slideshow.

Then folks found out they didn't necessarily want all that metadata along with their content, so shift-ctrl-v was introduced. Somewhere along the way, patterns emerged for many folks (like myself) where matching the target formatting was the more common case. This is especially true among coders.

It's too late to change the default for everyone, but this tweak allows for some of us to tailor the behavior more closely to our own personal workflows.