I understand your points and enjoy this friendly discussion. But...
bastion, on 04 March 2011 - 04:07 PM, said:
The worst that can happen? Data destruction. It depends greatly on the nature of the file being opened and the application the OS chooses to open it. But some effects are:
You will wait for the app to load and the document to be opened. This can take quite a lot of time and system resources depending the file and the machine.
Certain data files will change automatically as a result of being opened. Undo or close-without-saving is unlikely to exist in exactly those scenarios.
The consequences of opening an application by mistake can be completely arbitrary, and need not be overtly destructive to be undesirable.
Metadata absolutely will change. That can have consequences in the future depending on other processes running on the machine.
Waiting for the app is not an issue. Thanks to smooth Mac OS X multitasking, I simply put it in the background and it will have no effect on other processes unless some heavy processing is going on. Later, I can quit it from Application Switcher without even switching to it.
I see your points about metadata changes, but on the whole they're not significant. 90% of the time it will simply be the OS X "Last Opened" datestamp, which isn't something anyone wants to rely on anyway. Besides, if you put that risk next to the risks of accidentally renaming files, usually renaming files will cause more mayhem.
bastion, on 04 March 2011 - 04:07 PM, said:
There is no cost inherent in putting a file into rename mode, which is what "enter" does on the Mac. For any cost to manifest you have to type additional keys and then commit the edit before you realize you've done anything. How often does this actually happen to you? And seriously: Losing track of a file within its folder is "far worse" than outright destruction? I can't agree with that.
Let's remember that I wasn't the one to bring that up first. Many people have, in the "Return vs rename" debate over the years, so it isn't exactly rare. In the context of speed oriented keyboard work, where a string of shortcuts is pressed, a Return may be followed by more key presses. This is where a file may be renamed before you realize it happened, and as the other poster pointed out, before you overrun the (why, Apple?) one single Finder undo. And I don't know where you get the "outright destruction" thing since generally, opening a doc in an app is not a straight path into "outright destruction," where there is little difference between being unable to locate a file because you can't figure out what its new accidental name is, and the file being destroyed outright...
Obviously we just agree to disagree.