Personal preference?
Also, within the context of the conversation at the time, the 4365 wasn't available in the U.S. so that could possibly have been a factor in the answer, although I am pretty sure that it was primarily that he was very happy with the way the S4700 had come together. Another factor could possibly have been how other people at JBL responded to both systems?
Basically what it comes down to for me personally is, if I had a pair of S4700's they would stay stock. I wouldn't screw around with them. They are plug and play. In short, I would be happy with them just as they are. I have a pair of Tannoy loudspeakers that I feel the same way about. I will never modify them.
The 4365's on the other hand I consider fair game. I like the individual components, I like the fact that some of them are also used to great effect in the K2-S9900 and DD65000. I like the modification potential.
Despite his answer I went with the 4365 components.
Oh and yes, crossover networks are a major component.