It is definitely a good idea to develop more powerful Aikido attacks - more focus, more power, more intent - you could even call it kiai, really - but that's not the same thing as the issue where people from other arts call Aikido ineffective or unreal.
Mr. Hein's video is good for disabusing the notion that we will finally get the chips off our shoulders if we just do things with "more power." Our attacks have a contextual basis in our training, we use them to study our technique, and we study our technique and see where that leads us.
The boxer isn't criticizing the lack of power in our attacks, she just doesn't understand why one guy is standing there in hanmi, waiting, and the other guy steps in with a straight full-power punch and that's all he's going to do. Boxers don't hit you with a lot of power until they feel like you are both positioned such that you will have to take that power. There is a lot of movement and testing and feinting to get there, which Mr Hein points out is not part of the heritage of Aikido.
The knife fighter, on the other hand, would probably criticize the power in your attacks, because a sharp knife is best used with the bare minimum amount of power to cut, and that's not much, unless there is a particular kind of armor involved.
incidentally each of those fighters might have criticisms of how the other trains, because for their context it isn't beneficial.
Well, it's obvious that a boxer may use quick, non committed jabs and an attacker with a knife will probably use fast small moves instead of a full step from a distance.
But, imagine that you have a beginner in the dojo and all of a sudden you just jab him fast. And you repeat that in every attack.
Not only he is gonna get badly...bruised but also, and that's the worst, he will never learn anything. You can't start teaching a six year old how to write by asking him to write an essay on the greatest authors of english literature on his first day at school.
But after a level when he has learned the basics the attacks must become, gradually more and more demanding and this is the way we train, we use the basics and also we use attacks like a close fast jab with the front hand with no step at all.
I know the majority of the dojos neglect that and give a wrong impression, but that does not reflect the true effectiveness of aikido as a martial art, only their own, personal level of effectiveness...