Prometheus was a Titan. He helped people several times. But was he praised as a god would be? Gaia was the very mother Earth. Was she loved as any other goddess would be? Atlas held the sky up from crashing down on the earth. Was he respected for this service?

Why do all titans seem like cameos in the greek mythology? 

It seems like - Oh this guy, what was he? Oh yes the time itself. Yea that is just an old story.