I think this is a good example of where the valuation should be changed. Personally I think resource values should be divided by 1.5^(number of era away of the resource's use). Maybe not 1.5, but something like that.
Most of the time it doesn't matter. For all but starting cities, resources that a Civ doesn't have the tech for won't impact the city weighting.
I should have said that better - I'm not complaining about the majority of cases, which I agree are fine. But all the times where my starting location has been really, really atrocious are due to it not realizing the drawbacks of peninsulas.
I guess we are having different experiences. My worst starting locations have always been the "paradise in the tundra" starts. Peninsulas don't tend to be great, but they almost always have a lot of water resources that make them more valuable.
Bh