This has been an interesting read so far. To follow up on a couple thought paths in this thread:
1) For starters, people don't need to tell me that I should shoot manual etc. I shoot manually and set my exposures via incident light metering nearly all the time. That said - there are in fact times where available light is infact not constant. Theater is one such. Indoors with lamps is another (lighting from a few fixtures is subject to the inverse square law). So when you are shooting in highly variable light, an auto meteted mode is convenient.
2) I don't care about the future of film. What I do want is a break from film thinking in the design of digital cameras. The two main auto-metered modes (Av and Tv) make it sound as though you are setting only one variable (aperture and shutter, respectively) when you are actually setting two variables. In each mode, the photographer is manually selecting the ISO as well.
The problem is, there is no mode that let's you pick aperture and shutter speed and lets ISO become the dependent variable. The Mark IV comes closest to having this as a pure mode, but it is grafted on to M mode (with ISO set to auto) and so EC is not available.
A clean sheet digital SLR design would discard P, Av and Tv and create new metered modes named after the dependent variable. One of these modes (call it 'I' Mode) would have you set apeture and shutter speed and then the camera meter would pick ISO.
This is not a hugely important thing to me, but I thought it worth comment. P, Av and Tv have somehow carried over from film to digital even though the method to change ISO has gone from physically swapping films rolls to pressing a button.
The variable I care about the least is the one I want to be the dependent variable. This is almost always ISO. Say I'm shooting a stage play. The lights keep changing for dramatic effect so I am in an auto metered mode. I'm set up to shoot something like f/2.8, ISO1600 and 1/200. Suddenly the lights dim appreciably to two stops darker as the lead delivers a soliloquy.
In Av mode the camera would drop the shutter speed on me to 1/50 and I'd get blur.
In Tv mode the camera would hold 1/200 and keep the lens wide open (f/2.8 ) and underexpose the shot by 2 stops.
In 'I' mode the camera would hold 1/200. f/2.8 and select ISO 6400. Perfect.