It actually has two advantages, gadzook. Not only is it very reactive to heat (heating up and cooling down) but it also has some chemical properties that are desirable for sugars, egg whites and cream. There is a transfer of copper ions (chemical reaction) that ehnances carmalizing of sugars, and it also makes for more stable "foams" like whipped egg whites and cream.
The down side is that our bodies can get overloaded with copper - so copper is not something that you want to cook in everyday.
If you can find a copy to read - Shirley Corriher talks about this in her book Cookwise, and I think Harold McGee talks about it in his book On Food and Cooking.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain