As far as I can remember, a traditional film has roughly around 16 million of photo sensing elements. That's why the traditional camera is still far better than the digital camera, if you want to enlarge the image for a wall-size poster.
Larger the lens means you can get more lights into the lens, but the quality of the lens is far more important than the size. A good quality lens will reduce the optical aberration(chromatic or spherical), distortion (pin cushion/ barrel distortion...etc) and vignetting. It costs a lot to get a good lens, that's why Leica's lens could easily go up to thousands of USD.