That tiny little arc-reactor, that damage to his body, that was as much a part of him being Iron Man as his motivations to escape his prison. Yet, it was simply just thrown-in like some sort of additional info, which seemed to bother me. I would have liked to see more development that just "op, i'm gonna get fixed too!"
Is this an honest "why would you do this?" question or do I simply care more than most?
EDIT: This is a question of why if was barely covered in the film, not why it happened.