The mystery of the D80 and AI metering has become central in my mind.
It is no mystery. The D80 is a consumer camera, just like its
predesseror D70, and AI metering is a pro feature only included in
the pro cameras.
I guess the main reason for this is just plain and simple
marketing. They want to have a diverse sortiment of cameras
catering for different needs, and they cannot stuff every feature
into every camera and still sell different models. Well, they could
just make the D2X and be done with it, but that would soon
eliminate them from the market.
So they make different camera models with different feature sets.
And AI metering has not been part of any consumer grader Nikon DSLR
to date, and probably will not ever be.
If AI metering is so central to you, save up the money for a D200,
its a great camera and the price difference to the D80 is not by
any means impossible to get by. If you could afford a D80, you
could fairly easily save enough to get a used D200 as well.
I totally agree with you that metering with AI lenses is a bonus (I
have it on my D2H, and sometimes miss it on my D70S). But when it
comes to old manual lenses the D80 have one major improvement over
the D70 -- the viewfinder. Setting manual focus will be so much
easier with the new brighter wievfinder. Lacking AI meterining is
in my world a rahter minor nuisance in comparison.