100% is the way to be. Once you get there, then you can start having useful conversations about how to make the coverage more meaningful. But first, you have to make sure that every line is run at least once without crashing (except for the lines that are supposed to crash things - those you need to verify DO crash things).

Interestingly, once something is designed for testability it is more likely to not have bugs. But saying that therefore you don't need the tests is silly, because without the tests you wouldn't have designed for testability.