Just a few thoughts here based on my experiences........
Good aikido does not force injury on uke. It just returns the amount of force the attacker used in his attack. And if uke cannot do ukemi well, that force may graduate to something that is dangerous as we increase our intensity. Nage's only being nice when he slows down your attack.
In the cooperative training environment that prevails with most Aikido I think that your idea of good Aikido is the stretch goal.....the ideal..... one that is still way beyond most of us. In a non-training environment the variables are so numerous that the timing of the ensuing events may preclude any idea of "helping" the attacker through it.
Talking injuries, most of those I received in the cooperative training environment came as a result of errors on the part of nage in form, method, understanding the where on the mat, understanding their own bodies and skills and stuff like that. I have had both shoulders separated (minor) with the right one more than once. All of the times because I was loaded up and had no place to go but down....they collapsed, they threw into space to small to land, they shorted me...... I quite taking falls a long time ago....hips, lower back and other areas told me to give it up.
In all cases when I find myself unable to choose an ukemi, I just pray that my body would do something right when I hit the mat. It's always a happy feeling to find myself still alive after one of those. But in all those events, never have I felt nage was out to hurt me or throw me. It always felt like I got caught in a whirlwind and was loosed after a time... Does that make sense? The hurricane's not out to get you... You just happen to be on its path.
Way back most ukemi I took in seminar settings was still a cooperative environment for the most part with the instructors teaching....not always with the individuals traveling with they though. There were a couple of these Shihan whose general attitude was one of demand compliance. You always made sure they beat up their personal uke first so you knew what was coming.....then if he got to you,,,you stayed ahead of him enough as to not get hurt and to not make him look bad........