Long before 2.4 was dreamed of for consumer RC use, I regularly flew several brands of equipment. Like today, most were very dependable so I'm not a brand snob or fan boy. I was an early adopter of JR and Hitec digital servos but was burned bad (very frustrated) by what I called "JR's servo of the month club". As problems developed and there were many, I would receive replacement servos only to notice that the only thing the same in the replacement servo was the label! I mention this only to illustrate that being first to the party (first in the market) is not always a good thing. With regards to the servos, Futaba digital servos didn't show up in the market for quite some time after JR introduced them and I don't remember Futaba having anywhere near the problems that JR had. I'm sure that Futaba and other companies learned from JR's mistakes.
Being first to the party can lock you into choices that are hard to get away from later on. Perhaps that is the case with Specktrum and JR satellite receivers. Coming from an RF background, I never quite understood why they went that route they did with the remote receivers but once the choice was made, economics of production probably locked them into the choice for some time to come. The system has certainly not proven itself to be any better than the dual antenna receivers so common with other companies and now of course from JR as well.
So why did Spectrum go with the remote receivers? I'm sure engineering thought it was the best system at the time. I wasn't there so could certainly never second guess their decisions. It is what it is as they say .......