There's always two sides to every coin.

You might see it as a way to instill a sense of accomplishment and pride in yourself, but others will abuse this system. It would promote elitism. Say we have a new player. He only has a single rank 30, and thus his collective level is low. Then we have a bunch of people with multiple R50s and a high collective. They might not invite that low player because it's obvious he's new. People might discriminate against new players and require a set "Collective" in order to join groups to perform certain tasks.

Similar to what happened with Gearscore in WoW. I think it would cause more trouble than good.