My number-one wish for a NGS: Undo! Take, for example, rm. The hoops we have to jump through when accidentally rm'ing a file are ridiculous [1]. But in most cases (smallish, non-secret files), rm should be trivially undoable. Windows gets this right: By default, files are not deleted, but moved to trash. If there is not enough space in trash, Windows warns you. Or, if you really want to delete a file instead of movin…
Although I kind of agree with you, I'll play the devil's-advocate: If you actually care about the file, it should have a backup that you can restore from anyway. And, depending on the file, that backup should be source-control.
Yes, people should maintain backups. But if people don't, for whatever reason (maybe they've never heard the word "backup" before; maybe they typed the wrong command and thought they had backups all along, etc.) shouldn't be screwed if something goes wrong.