The reason why you see the Defenders camping their bubble is because that's their only ability... one that is trumped by every other Super, to boot. Defender can't Blink. Defender has 3 grenades that only deal damage on contact or within a small radius. Defender has the shortest range and least damaging melee that only has an effect after you've already killed someone. Titans don't have very useful melee/grenade abilities and their Supers, while seemingly overwhelming, are predictable (FoH) and easily counterable (WoD).