Dismantling the Friends series finale which was seen by 50 million people, as Corden points out for the sake of a new series does not seem worth the risk—which helps explain a low-stakes reunion like this one.
How Do You Watch the Friends Reunion Special Internationally? The ever-mugging James Corden was, for whatever reason, given hosting duties; the portions where he lobs softball questions at the six cast members are probably the weakest parts of the special.
Thus, making it very clear, how Ross and Rachel were able to have the truest chemistry on set.