The jury didn't reject the DNA evidence, but how it was collected. DNA was still fairly new when the OJ Simpson case occurred, and its collection did not yet have set protocols. Different witnesses cited different protocols, that could have led to the evidence being tampered with or contaminated. This cast reasonable doubt on the accuracy of the DNA evidence.
If I were on the jury, I too would have been skeptical of the accuracy of the DNA evidence as the defense revealed opportunity for tampering and contamination. That accompanied by a key detective taking the 5th when questioned about racist statements, the glove not fitting, alternative explanations of the shoe print all would have left me with reasonable doubt as to OJ's guilt/innocence.
However, if the case had happened today, it would have been more airtight. Protocols have been standardized as to how the evidence has to be collected and catalogued, this makes it very hard to tamper with the evidence, and protects against contamination, and makes it more reliable. The motives of key investigators, and the fact that the glove didn't fit, would still have to be weighed against the DNA. And the DNA only would prove OJ Simpson was there, not that he was the killer.
He went there intending to kill them, found that someone else had beat him to it, and fled correctly fearing that he would be the prime suspect. That would account for evidence indicating he was there, but he would be innocent in that case, and it is a plausible alternative explanation. That leads to a verdict of "not guilty" even if he did do it.