> That sounds intuitively reasonable, until you look at the current situation where every time you copy paste text between programs that support formatting, you have to cleanse it by pasting and copying through Notepad, or it will do the wrong thing.
Most programs which support rich text copy-pasting have "paste with formatting" versus "paste text only" options, with the ability to change the default. If an application doesn't, that's the fault of that developer, not the OS semantics.
> Note that fixing this would have negative cost: just don't bring any formatting information with copied text.
I like having source formatting with my pastebins, and most non-technical people do as well. For example, when emailing a code snippet to somebody, I love keeping the syntax highlighting from my editor. And the option to keep the text only is always right there if I need it.