My ex was certainly vulnerable in that way and I will freely admit that there is an attraction to playing the hero in the relationship. What I can tell you from that experience is that it gets old. Real old.
That expressed vulnerability does a couple positive things... first it provides a reason, or excuse, to develop intimacy besides "I'd like to get in your pants", which is a struggle for many guys who don't want that to be the reason they get involved with someone. Second, none us of are invulnerable to the ultimate flattery of being someone's hero. Not worshiped, but appreciated.
The problem is that with real injuries, real problems, they heal over time with effort. If they don't heal they weren't real, or you didn't really help. In either case the hero mystique dies a quick death. If you're far enough into the relationship at that point to have self-sustaining intimacy then that's alright, if a bit uncomfortable. If not, it can create enough of a barrier to starve the relationship out.
Obviously the solution to the short term planner is to create a new situation in which the other person can be a hero to get that feeling back. And thus the manipulation begins.
For that reason I'm now extremely wary of anyone who claims they need help but don't really. I'll move a sofa if you're too weak, but if you ask me to do it again, you might get the robot.
I'm not sure exactly how the super-skinny fad fits into that, but I find it about as attractive as someone with severe emotional problems. They're still fine people I'm sure, but my natural inclination is not "I want to get romantically involved."