Rowles had pleaded guilty to a charge of intentionally inflicting grievous bodily harm and was sentenced to seven years and one month imprisonment.
Taylor had made a pre-trial offer to plead guilty to wounding with intent to cause grievous bodily harm, provided the attempted murder charge was dropped, but the Crown declined the deal.
In the Supreme Court's decision released yesterday, it said the Crown was open to proceed with the attempted murder charge against Taylor and there was "ample evidence to support a conviction on that basis".
"It was likewise open to the Crown to take the view that the evidence supported the inference of intent to kill in Mr Taylor's case but that such an intent might be more difficult to establish in the case of the co-offender," the judgment read.
"The applicant's conviction on the charge of attempted murder explains the apparent disparity in sentencing between himself and his co-offender."
Taylor's lawyer, Marie Taylor-Cyphers, also argued the trial judge should have told the jury they could only infer an intention to kill if Taylor had recognised that the death of Vincent was "virtual[ly] certain".
However, Chief Justice Dame Sian Elias, Justice William Young and Justice Mark O'Regan ruled there is no need for judges to give elaborate direction in respect of an intent to kill, which "is consistent with normal practice".
The Supreme Court also ruled there was "nothing untoward in the directions" and "no appearance of a miscarriage of justice" by the trial judge when they summed up the effect of alcohol and drugs on Taylor on the day of the attack.
Vincent suffered a total of about 81 deliberate blows to his head or body, the Otago Daily Times reported earlier.
Vincent was placed in an induced coma for 12 days after the attack and spent three weeks in the hospital's critical care unit with traumatic brain injury and related complications.
He has since gone through an intensive neurosurgical treatment and rehabilitation.
The Court of Appeal decision described the attack as "repetitive stomps" to the face and head which lasted for one minute and 39 seconds.
"Mr Taylor delivered 23 single-foot stomps to Mr Vincent's head. On an additional three occasions, Mr Taylor placed his hands on a shop bench either side of him and lifted himself up so as to be able to stomp with both feet at the same time on Mr Vincent's head," the decision read.