It seems that some people really like the KeyBind functionality.

From @elguapo1991:

That makes sense. I definitely would appreciate a simple text field for the feature in a future update; I sometimes have the same spell bound to different keys across specs so the visual reminder is helpful despite muscle memory probably "knowing" which key to press.

We should be able to bring this back in a more customable way by using a simple text field in which the user will be free to input whatever he want. In this way, we won't have to manage any "layout" or special keys problems. This will all be on the user side. Like this, both side win.

Also, @claycle is requesting the following functionality:

Testing the AddOn Today, immediately came across some feature requests: Toggle to show KEYBIND of spell on the icon.

We should be able to add such an option to enable/disable the display of KeyBinds globally.