NagaBaba, just look at ukes with Chiba sensei, it is very rare that they take high breakfalls and as you know he is one that can throw you very nastily. It is my understanding that Chiba sensei is not a fan of high breakfalls.So I think aikido can be done without that kind of ukemi.
It is true; sensei doesn't like high flying breakfalls. He was witness of bad accident that happened few years ago. However I've never experienced from him any nasty throws, nor I witness it last 20 years.
However, if you follow this kind of reasoning, look at many seminars with Tamura sensei, a lot of students didn't take ANY falls, they just kept bending back a little…a real disaster if you ask me…Were they doing aikido? Or just pretending to practice?
How you want to develop a full power of the throws in aikido without uke being able to safely receive such throw?