"Hit harder" in the sense that an elbow injury can cause much longer DL time and have much more significant career ramifications. See the article Kevrock posted above about second-round TJ surgery.
Oh, if you get hit again, yes. But I bet someone who's had TJ already is a LOWER risk for additional elbow problems than a pitcher who's never had it. Mindfact for sure, but it seems this tends to strengthen the joint against future issues.