I believe it's bad UI because Text Selection is marking a range of text for manipulation (like copy, move, style changes, etc.). Of course, you might also like

I believe it's bad UI because Text Selection is marking a range of text for manipulation (like copy, move, style changes, etc.). Of course, you might also like to erase the text, in that case you can use the Delete/Backspace key. But to have any key also function as 'Replace all this text', when you're solely in a text manipulation mode just seems like a destructive action, where it wasn't explicitly commanded by the user (it might be explicit if you've experienced the behaviour before, but consider a novice user). I can't think of a good way to rationalize this to a novice user. I should have clarified in the article about this. I will add this clarification to my article.