Why use 35mm standard focal lengths for FOV crop sensors?

Why don't camera and lens manufacturers just indicate the equivalent length on the lens instead of forcing us to deal with FOV cropping? The 35mm standard worked great for film, and of course full frame DSLR's but those only make up a fraction of the DSLR market. Why not create a new standard for smaller sensors? With so many different sensor crop sizes from 1.3 all the way up to 2, when will we get closer to a digital standard for digital SLR's? Is it cost? It seems more expensive for manufacturers to make proprietary sensors in different sizes than to standardize one like what was done with film. No fuss with crop equivalents. I see this as hindering the proliferation of cost effectiveness among the digital camera industry (mainly those who buy them) as many manufacturers make their own sensors. Maybe for the film camera industry, having different manufacturers make film the same size benefited everyone involved. Do you agree? I welcome all opinions.

Maybe it would be cheaper for both consumers and manufacturers if they didn't make their own sensors in different sizes. And maybe someone would figure out that a digital sensor doesn't have to be the same size as a 35mm film frame, being so expensive to manufacture a digital sensor that size.

Because the focal length of a lens does not change.

I am in agreement with the answers above. Focal length is a physical constant (once you allow fro zoom lenses...), so it should just be called what it is.

I see point and shoot cameras that show the equivalent focal length on the box, but the user doesn't have the option to change the lens on those cameras. This is their way of leveling the playing field so that people don't have to do crop calculations. Can you imagine if the general public was expected to choose between a 1/1.8" sensor with a 5.8-24 mm lens (Nikon CP 5400) and a 1/2.5" sensor with a 5.8-23.2 mm lens (Canon SD850)? Are they almost the same or really different? Mass confusion would follow along with a lot of disappointment.

Think about Nikon or Canon offering different sized sensors in their DSLR's. Any Nikon lens can be used on the D3, where it is what it is without any crop factor. Should Nikon put two different labels on their lenses indicating what the equivalent focal length is for both sensor sizes? How about Canon? The last time I knew, they had three different DSLR sensor sizes. How about Sigma, Tamron and Tokina? Would they make the identical lens using different mounts and call the focal length something different for each different
mount?

I have an APS camera (original Canon Elph) and the lens is marked 24-48 mm. I am not sure if this is in terms of 35 mm equivalency or actual focal length and I can't find the manual at the moment. Given that the crop factor for APS film would be something like 1.4x, I don't want to just look at some photos and guess. I'd have to some current tests and I don't know if I coudl still get the film developed! I think I still have 1 or 2 "new" rolls around...

I think it is incumbent upon the user to just become familiar with what the focal length means for their camera. Personally, I am trying to stop converting my DSLR focal lengths to equivalent standards. A 17 mm is a 17 mm and not "just like a 25 mm lens." I'll still answer these questions with reference to equivalent lengths, but I'm trying to get away from that in my own head.

The camera manufacturers rarely make the sensors, they buy them in and they are made in 'standard' sizes. The larger the sensor the more difficult it is to avoid dead pixels and to get one that works perfectly (the drop out rate is 80% for APS size sensors) so the more expensive it is. There are benefits with smaller sensors depth of field increases dramatically, lenses can be simpler without vignetting etc.. so most development goes into cramming more pixels into a small a space as possible, the only downside is the heat doesn't dissipate as readily as the mass is smaller so noise is the issue.

This argument was raised years ago with the plethora of fim sizes available everything from 10" X 8" plate camera to 110 format. It was a silly argument then and it's a silly argument now, as Pooky says a 50mm lens is a 50mm lens why call it anything else?

Chris