"We show that a linear increase in the resolution of images under each microlens results in a linear increase in the sharpness of the refocused photographs. This property allows us to extend the depth of field of the camera without reducing the aperture, enabling shorter exposures and lower image noise."

You're right that you still need good, small sensors to enable good, small lenses, but my ultimate point is that digital camera sensors scale with advances in silicon. Lens technology is much, much slower to advance. The more of this we can do in software (and thus, silicon) the better.