Gotta Catch them all....
Sephiroth is my only Wind Eidolon so far and I have 1 more to get before max LB (which means I have to farm fighting her in the quest), and before the Sandolphon event Yinglong was my only lightning Eidolon. I'm backing off on Yinglong right now for LB Mat for my Kams but at some point I still want to go back and Max LB her. I just want to have them because I can. Same Reason I want to collect all SR and SSR Weaps, I just want to have them.