But agnosticism is technically just a modifier, not a separate party. And it doesn't necessarily imply weak commitment. There are agnostics on both sides who feel very strongly about their stance, despite admitting that there's no hard empirical evidence to base their beliefs on. I believe the fence-sitters you're referring to are called "weak atheists". (Although being one myself, I'd prefer there was a different "official" term for it, as I don't identify with strong atheists at all and think the theist/atheist split has an absolutist stigma around it whereas I see a gray area between the two.)

That said, I've never understood the logic behind fully committing to one side of the other. It's not about fearing whether I'm right or wrong, it's about a lack of convincing evidence from both sides. That and the fact that I really don't see what difference it makes either way; it's just not important to me.