The potential for wizards to abuse their power is already a thing in some campaign settings where they are controlled and magic is regulated. Even within the same setting, people have different concepts of right and wrong, legal and immoral. If they feel violated and are strong enough to seek revenge, welcome to medieval society. Just don't kill anyone important or you'll end up in jail.
The same way a doctor's education level gives him the right to decide treatments for patients, even should they be mind-altering or potentially lethal. Granted he has to pass a medical exam and gain a license, but what exactly do you think people do in wizard college? There are even settings where not having a license to practice magic makes it banned.
This was part of the same point as the wizard for a reason. Lawyers receive the same education and granted rights associated with it as a wizard might. While a lawyer is chosen, he is also sometimes appointed. He can also take matters into his own hands when the person is deemed incompetent. His ability to choose between good and evil pertains to his knowledge of the law and how it's far from black and white. Casting Charm Person may not fulfill a societal role but how is helping a witnessed murderer escape justice doing that? Seems more like anti-societal aid yet permission exists for it.
If he's hired, he requires might. Without might, he has no right to attempt to dispose of unruly patrons. Even when not hired, there have been many incidents at bars where I or another person has had to step in and throw out the unruly patron or subdue someone causing a scene. Was a hired by the bartender for this? No, my muscles and propensity for meeting out justice say it all. If anyone disagrees, feel free to throw me out too. If you can.
Per the Suggestion spell:
The suggestion must be worded in such a manner as to make the course of action sound reasonable. Asking the creature to stab itself, throw itself onto a spear, immolate itself, or do some other obviously harmful act ends the spell.
If the suggestion is reasonable to the person being suggested, it obeys. If it is not, or harms itself in any way, it does not. In what universe would this spell allow anyone to rape someone unless the idea of intercourse with the caster was already a reasonable suggestion to them? It falls under obviously harmful acts otherwise.