Calcification of your arteries is a good thing.  It stabilzes an atheroma making it safe.  Without the calcification, atheromas put you at risk of a cardiac event or stroke or pulminary ebolism.

The presence of calcified arteries proves you have had atheromas (generally only atheromas calcify).  Low CAC scores in old people prove they are the kind of person who probably doesn't develop atheromas at all... .and high CAC scores in young people proves they are developing them very rapidly.  However, high CAC scores in old people and low CAC scores in young people don't tell us much.  With CAC you can't see how many risky non-calcified atheromas exist, only proof that there used to be some.

I do think Americans are lead to consume too much Calcium, based on bad science around osteoperosis.  Just get sunshine and exercise and don't worry about the calcium... either way.