It's a good question. It wouldn't take much to look at the plays where he's been hurt and see what's in common. I don't think it had anything to do with the play called (and also don't buy that our plays take any longer to develop than any other plays. Like every offense in the league, there are multiple options at multiple levels on every play. If Romo thinks he can buy some time in the pocket to get to a matchup he likes, that's not on the play design).
What's he had overall? The two broken collarbones. The rebroken collar bone when he came back too fast. The punctured lung v. SF that he played through, the compression fracture v. SEA, and the broken transverse (missed TE blitz pickup v. Commanders) that he played through.
It seems to me that he gets into trouble when he leaves the pocket and then stands in there to make a play with a defender bearing down on him. He just takes the hits more than some guys do. Does anybody remember what the hit was that punctured the lung in SF? Was it a blitz or him getting flushed again?
Either way, he's a tough dude. Until somebody explains why they believe his bones might be more brittle than they have been previously, I'm going to chalk it up to him being willing to take the hits more than most guys, a little bit of rushing him back last year, and some bad luck. Beyond that, it's the sort of thing every NFL QB has to deal with.