I am in full agreement with Dan Harden above. I remember, still an active aikidoka in Japan, age 24, telling my truly formidible instructor in Araki-ryu about some of the abuses I (and others here) enumerated. He looked honestly puzzled and said, "Are you telling me that the teachers do this and the students think they are strong?" He, far more precocious than me at a younger age than my 24, described joining the NihonDaigaku Aikido club, a very aggressive club led a very prominent, very brutal shihan - already a judoka and kick boxer, he lasted a week. At that point, he took ukemi for the teacher, who tried to hurt him and said, "OK if I fight back now?" And didn't wait for permission.
Stopping the teacher's response cold, he disdainfully pushed him aside and got his gear and left. And given his reputation in other circles which I shan't mention here, he, unlike most youth who quit a university club, was left utterly alone - no retribution whatsoever from his seniors, FWIW.
Additionally, some thoughts on George Ledyard's and Peter Rail's post - and also concurring with Peter G.'s point that we should try to hold our teacher's accountable for their legacy, this being contingent, however, on our own level of accountability. Whatever level of skill I've attained in the various arts I've trained - and more generally, bodyskills - has come from four things: 1) training itself - putting in the mileage 2) Finding teachers who actually know something 3) Courteously, persistently demanding answers from my teachers - putting them on notice, directly or subtly, depending on the quality of our relationship, that I am only training to learn - EVERYTHING. I recently told a friend of mine, who has trained with a teacher for well over twenty years, that he should formulate the questions to ask his teacher why, after all this time, given his true dedication to training, he is clearly many levels below his teacher. In other words, "what have I not been taught? What have I not noticed? What have I not listened to?" But I also believe the teacher only "owes" the answer to those who offer the PASSION (I'm using the word in it's original usage - note "the Passion of Christ" is both ecstasy and torment). If one doesn't offer that level to one's teacher, one is owed nothing. In the latter case, take anything given as a gift you haven't earned. 3) Never get offended when my own lack of understanding or skill is pointed out. I recently got offended at a teacher of mine who apologized after for pointing out a clear deficiency in my "structure." My sense of offense was not the way he crudely pointed it out at first - it was that he felt I might be the kind of person who would have hurt feelings at the truth. (As a teacher, myself, I "write off" people who are so offended, who cling to the attainments they have). Similarly, if a teacher is off the mark, I am not offended either - those who defend themselves, saying "that's not fair," "that's not true," when it comes to technical corrections are more concerned about their own image and attainments than learning, because rectifying the misapprehension of the teacher becomes more important than further information.
In a moment of alcohol inspired affection and honesty, one of my teachers in Japan said the following to me, after eleven years together: "Ellis, I'm going to teach you everything I know. So I'm putting you on notice, I'm going to treat you like hell. I'm going to find fault in everything you do, cut you no slack whatsoever, and accept no excuses or explanations without instant understanding and ability in what I want. I can't believe I'm telling you this, but you are a foreigner. A Japanese would know without my saying so what I was doing. Because you are a gaijin, you might think I merely hate you." Kindest thing he ever did. Because he was true to his word. I was sick to my stomach with adrenaline for the next two years. It, an accentuation of the relationship we already had, played havoc with my entire life - in retrospect, some aspects were destructive for a long time. But I learned what I desired, and that havoc - mostly psychological, but also physical, was what I was prepared to sacrifice to do so. (But, quoting Dan above: "Severe training can be dangerous, I have had my share of injuries with students but they were random accidents or done under full fight training."). My teacher received - and was willing to receive - as good as he got. This is something different than the abusive behaviors we've been discussing.