Getting back to the original post. I think the answer is pretty straightforward.
Pre-digital meant that film and camera were two separate things. You bought a camera and you bought film to go into that camera. The variety of film available far exceeds the variety of sensors currently available. You had slow speed, fine grain B&W (slow being about ASA 25) up to "fast" 800 ASA, with most people shooting 400 Tri-X. Maybe not the best, but it was the most readily available and sold the most in the U.S. at least. Then you had color print films and color slide films, all in various flavors of speed. Not to mention Tungsten and Daylight versions.
In addition, you had many different film formats, from large sheet films to tiny drop-in cassettes, all with a variety of speeds.
Today, every camera uses only one "film" and that's the sensor. It has to do everything and it is part of the camera (no changing sensors at least for now). B&W, color print, color transparencies, high speed, low speed, tungsten, daylight, etc. all in one sensor. So, really, it should come as no surprise that there are a few (and really it's only a relative handful of varieties of sensors that are available) different flavors of sensors.
One more thing. The quality of that sensor, even in the smallest formats, vastly exceeds the quality of most films. In the old days it was generally conceded that even the cheapest lenses would outperform the film's resolving power. Today, sensors are pushing the limits of what lenses can resolve.
Bottom line: The choices in film that consumers used to make are now incorporated into the camera. So it should come as no surprise that cameras need to offer more variety for consumers to choose from. After all, who wants less choice as a consumer. I certainly don't.
