Stop talking like screwattacks battles are perfect. They're far from that. Hell, they showed the scan of Supes lifting 6 sextillion tons, yet in the stats only put him in the quintillion ton range. They also even showed Supes flying to Jupitor in less than an hour which is about 16x the speed of light, yet put his speed at about 8x the speed of light.
They obviously wanted to make the battle atleast entertaining animation wise so they boosted Goku so that he could actually stand a chance vs Superman. Hell, they knew beforehand that Superman was multiple times faster than SSJ4, yet they had regular Goku keep up with him, they knew Supermans durability was far more than anything SSJ4 can dish out, yet they had regular Goku faze him. They're obviously not going to make all the fans wait over a month for this battle, then make it how the battle should actually happen and have Goku look around like a confused puppy before being splattered with a single punch.