As well as being a bedrock principle of the law, it's also basic common sense. If I accidentally step on your toe, that's obviously different to me deliberately stamping on your toe in an intentional attempt to injure you. If you set out to deliberately injure your colleagues then this is OBVIOUSLY different from doing the same thing accidentally and should be treated differently - and anyone with a working brain can see this.
The idea that "intent doesn't matter" is preposterous. Accepting it as a premise leads to insane and preposterous conclusions that no-one believes. People who say that "intent doesn't matter" don't actually believe it.