Now that you point it out, it does seem that the Titans are at a bit of a disadvantage. But giving them a ranged super kind of gets rid of that "I like punching things" vibe they have going. What if instead, they got an increased defense against melee type damage such as those insta-kill stomps. That way such attacks would still insta-kill warlocks and hunters (they shouldn't be that close!) but only take down the shields of titan (who should be that close).