Apple Patents Glass MacBook Keyboard That Bends Under Your Fingers

The first computer my parents bought for me was an Atari 400. It had a membrane keyboard, with a speaker underneath that would click every time you "pressed" a key, to simulate the feel of a keyclick.

Membrane keyboards sucked. The problem is that your sense of pressing a key seems to be based more on how much your finger physically moves, rather than how much pressure you exert. It's pretty easy to demonstrate. Close your eyes and move your finger by (say) 3 mm. It's pretty easy to do consistently. Now put an item weighing about 50 grans on you finger and try to guess its weight. It's really hard.

I think what's sending designers down the wrong path is that they're assuming all you need is haptic feedback to get a keyboard to work. It's not. The haptic feedback is just confirmation that you pressed the key. Since the feedback happens suddenly after you press the key, it's useless for helping you during the act of pressing the key. OTOH, the act of the key physically depressing gives you continuous feedback as the key moves down. Once your fingers learn that the key needs to be pressed x mm to activate, you can accurately and consistently predict how much further you need to press before the key will activate. That allows you to anticipate when the keypress will register, and begin typing the next letter even before you've typed the current letter.