John 16:5-11
God's Plan for the Holy Spirit
5 "Now I am going to him who sent me, yet none of you asks me, 'Where are you going?' 6 Because I have said these things, you are filled with grief. 7 But I tell you the truth: It is for your good that I am going away. Unless I go away, the Counselor will not come to you; but if I go, I will send him to you. 8 When he comes, he will convict the world of guilt in regard to sin and righteousness and judgment:
9 in regard to sin, because men do not believe in me; 10 in regard to righteousness, because I am going to the Father, where you can see me no longer; 11 and in regard to judgment, because the prince of this world now stands condemned.
When Jesus said that is good that He is going away, maybe interpreted that He knows that He is going to the cross...He knows that He will be dying for mankind's sins...He knows that He will be paying humanity's sin debt...His death on the cross pays for all of sin...God now has seen justice for the morality of mankind...Mankind's Savior has died for us...Justice is seen by a Father in Heaven...Those who love the Father and Son see both the tragedy of the Son's death on the cross, while paying for our sins...
So He must leave His disciples for this reason...And then He can send the Counselor, the Holy Spirit that we need to be in us...