Exactly, he starts off very flawed and grows from it. He's not brave or towering, he is slimy and a trickster. And its him fighting those flaws that allows for not only his growth, but towards him becoming a truly heroic person. Its relatable, because many boys are falling into that listless, directionless existence and the idea of escaping through finding love, friends, or a cause is inspirational.

So while guys like Optimus are great examples in their own right, so too are the ones who need to grow into being one. Shit one of the War/Fall of Cybertron games outright calls out that Optimus is unwavering and powerful through conviction on his own, but lesser men under his command need morale and supplies to keep going.