Firefox

I just want my backspace key to go back a page in my history when I press it, LIKE IT USED TO BE FOR 20+ YEARS.

But no, this is apparently a "poor UI experience", so I have to put my hand on my mouse, locate the pointer, move it to the back button, and then click.

At least Firefox allows you to rummage around under the hood and set it back.

Yes, if I could I would un-bind all keys, then look at the list of possible actions and devise my own keyboard control scheme to my liking. And then I should be able to export that to a standardized keybinding file format and carry it with me to other computers and preserve my keybindings.

Games often suffer from the same issue.

I've even made a list of features a keybindings control should have.

Ability to bind multiple keys or key combos to the same action
Ability to delete all keybinds, save keybinds, restore keybinds, undo keybind choice
ability to bind any keyboard, mouse or joystick element to any action
ability to set if the action is HOLD or TOGGLE
ability to bind a key to more than one action
ability to quickly find keybind duplicates 
all actions should have an explanatory tooltip message
when binding a key that is already bound elsewhere, there can be a warning, but enter/ok should just bind the key as requested and not unbind the other
there should be a way to set a key which will change the keybinding to another layout (I think they are called keymap layers, this is becoming a builtin keyboard feature)
reset keybinding to default, should not be something that happens by accident
keybind changes should not require pressing "save" for them to take effect
it should be easy to unbind one key from an action and to unbind all keys from an action 
setting a keybind should not be annoying (you click the action, press the key, it is bound, don't ask a bunch of questions)

Whoever made the decision to bind Ctrl-Q (something right next to Ctrl-W) as Quit/Close Window needs to be shot.