No, it's very unlikely to matter. I've been flying without entering in the Secure Flight (including just earlier this week), and I have yet to notice anything.

My impression is that the requested data won't be used for 99% of passengers; it will only be relevant to a small fraction of passengers, whose name matches that of someone on some giant list somewhere. But I wouldn't swear to that, and my impression could be totally wrong. Getting a straight answer out of TSA/DHS is always an exercise in frustration.

Short summary: Don't worry about it. Ignore it. You'll be fine. Really. The odds of it mattering are slim to none, in my personal estimation.