Escape key should deselect any selected object
This would be extremely useful when you are zoomed in and a lot of objects are filled in your screen and there's no empty space around to click if you ever wanna deselect an object. Please map the escape key so that it deselects any selected object.
Egor Chistyakov commented
You can go to the keyboard shortcuts and assign a hotkey to Deselect All command — but not Esc.
Escape in Ai is used to cancel the current operation, so you can’t reassign it, or they would clash.
But if you are on Windows, you can dive into Autohotkey, which cans solve this and many more other problems with hotkeys.