I love my Titan, but you're right, it doesn't feel like he's suited for PvP. Sometimes a well placed bubble can turn the tide of the game, but sometimes it just feels like super-bait. That being said, I still main a Titan in PvP and that's who I went to Mercury with. The super bait can be helpful in Trials, and a high armor stat means I don't burn to death from 2 thorn shots.