Personal limit breaks would be nice but they would still need to spice things up. For example

Tank limit break skills, for those big hits in fights where you need it, each tanks adds only half the mitigation you need. both tanks need to use together
Healing limit breaks, an aoe heal with an added refresh for mp. no more everyone ressing bs
DPS limit breaks, hits hard, places stacking limit break vuln debuff on boss for 10 seconds making you want all dpsers to use them together for anime levels of destruction