Fun little story by Bruce Horn on folklore.org about the original Mac and how modes are sometimes good:

We went to quite a few stores in the week or so after the introduction, and found that, without exception, every Mac's floppy disk had a garbage name! They were all named something like ";lkakl;rt;klgjh", as if someone had just randomly typed characters to see what would happen. Which is exactly what they did.

In the Finder, the startup disk would appear on the desktop, in the top-right corner, ready to be opened. The Finder would initially select it; once selected, typing would replace the current name, following the modeless interaction model that I had learned in the Smalltalk group from Larry Tesler. This meant that whatever anyone typed when they first came up to the Macintosh would end up renaming the disk.

On the early Mac, just typing with any item selected renamed it, which caused all sorts of trouble.

The eventual solution for renaming that survives until today was: click to select and then click again to rename… but don’t click too fast, because that’s double-clicking, at that means something else. Windows, starting in Windows 95, did something similar, but also put rename under F2 – so at least you didn’t ever have to wait.

I liked the emergent behaviour from some graphic apps which put rename under ⌘R. It’s not that hard to make Finder work that way – see below – but I have always been curious why Mac or Windows didn’t steal this solution.