Lots of code bases have code coverage in some middle range, lets say it's 82.34%. What does that number tell you? Did the team write 7.64% more code this month that doesn't have test cases?
The point you're making is actually irrelevant to the discussion. If you explicitly excluded code, you probably have a reason for that and you take your chances. Ideally, in a perfect world, you'd have no excluded code.
Also, this method doesn't show when you remove excluded code or add coverage for it. In a perfect world you should have no excluded code, and in a perfect world you should have 100% coverage.
World isn't perfect though, and a good working product with critical features is better than one lacking important features but with '100%' coverage.
