It's not though. Running a team with 4 or 5 same-element characters is generally going to do more damage, and with no strings attached. Lilims are mainly useful for new players lacking a good grid and other eidolon options. The break-even point vs. a team with 4 same-element members and +90% elemental attack without elemental advantage is at around 40% assault skill, and 75% with elemental advantage.