Touch Type

Why do standard keyboards only have 2 keys that give any indication of what they are via touch? Keys F and J have little bumps that indicate to the user the key that their finger is touching.

Why not have different types of bumps for different keys? In the same way that blind people learn to read braille, the typist will, over time, learn to quickly recognize the textures and identify them with different keys.

This would enable touch-typing even when disoriented or with one hand.