Note that I'm not arguing about underlying reasons, just saying what the empirical results show. That's reality.

So if you try to predict software bugs using modularization (or lack thereof) or "if-then-else" branches, or whatever complexity metric you can think of, you'll get one result. If you try to predict them using simple line count, you'll get another result. The second one will have better precision & recall. So no metric so far has been shown to be better than simply counting lines. That's not an obvious result, but it's the truth.

Sadly, you'll have to believe me because I cannot find the studies right now.