I find that, despite the many rationalizations, most people who didn't apply for journals just didn't think they'd get on.
That might be true to some degree, but it's also way too black and white.
If I had somehow known that if I tried for law review I would definitely make it, would I have done the competition? Yes, because it is an important honor to have, and if it's there for the taking, you should take it.
If I had really wanted to be on it, would I have tried? Yes, for the chance to have the experience.
But (1) I knew that odds were that I wouldn't, AND (2) I didn't particularly want to be on it (time commitment much larger than that for other journals) or to do the competition (was about to leave country for 2.5 months, and wanted to spend time with husband).
At a certain point, you have to make the choices that are going to make you happy.