I also think that when we look at Aikido waza, what was the original purpose and design, why was it created and to answer what type of attack and attacker. The would also help I think in understanding how to avoid injury. It would help with why the uke is placed in the position they are placed and give insight to how to take the Ukemi. It is my understanding that Shihonage is one of those waza designed with the absent of Ukemi in mind. That might be the reason for the injury susceptibility and rate with this technique.
This is why we learn a specific technique, with a specific ukemi in our kihon waza (by we I mean my group). While the ukemi isn't scrutinized as much as technique, its still important..in particular safety points as well as how to actually go about taking ukemi for each technique.