If for instance someone in street aims at specific position (kick or punch) and produce it with a slight deflection so practically he hits his rival. So, for instance if the deflection is minor instead of hitting the nose for instance he would hit his mouth or eye. So should one emphasis his practice on the intensity of the hit (speed and strength) more than accuracy?
"Can I get a good shot in at the right range?"
Accuracy matters... but maybe not in the way you're thinking of.
First, you got to be able to hit a target that is moving. Range matters a lot here. Then you have to be able to hit it in a way that you successfully transfer force into it, instead of sliding or glancing off. Along the way, you also don't want to break your hand or wrist either. So the accuracy is less "can I hit their left eye" and more "Can I hit their bobbing head while moving and they're attacking me?"
And notice that to do all that, you'll need a certain amount of speed, accuracy, and power. (and part of what's influencing the power of the hit, is the ability to land a clean shot...).
That's what a lot of the accuracy training is in boxing and similar arts - you expect your opponent to slip and angle, and you have to deal with that. Even untrained people move erratically in a fight, and it means they're not going to be at exact angles to get easy hits in.
Workarounds to Accuracy
This is also why you'll see a lot of streetfighting techniques and some self defense systems will utilize "indexing" or "sticking" - grab the opponent with one hand and attack with the other - it makes it harder for them to move away, and gives you a direct, tactile sense of range and direction.
When you move to using larger weapons (sticks, machetes, etc.) you can pretty much give up tighter accuracy and accept range as your main bit to work on - connect with any part of their body and they'll be sorry for it.
When I train people for self defense, usually the first thing I focus on is using hammerfists/ulnar forearm strikes. It gives a broad striking surface, has a tolerance for misjudging range, is unlikely to break their own hand, and can hit with a lot of force without a lot of practice. It translates well to using things like self defense tools or knives as well. After that, then I focus on elbows and knees, which work primarily in conjunction with grabbing the opponent - again, taking care of the issues of range or accuracy.
As they do more training, and become comfortable with range and movement in action, we expand the repertoire and move out into methods that require more skill or complexity to utilize.