If you mean in current XI, they sort of already do. Rather than thinking of them as characters, they're more like Job+Gambit, because there's about a dozen healers, but some heal above certain HP%, some throw on Regens and use Cures only when below 30%, some use Haste/Refresh, and others remove status ailments, etc. If they released Gambits, it would obviate the need for most Trusts. Like I remember Ferrous Coffin uses Cure VI and Raise III and Haste, but had no way to resore MP. Apururu has Convert and Martyr, Cherukiki used Regens but no Convert, Mihli Aliapoh has Aflatus Solace's Cureskins but no Haste, etc