Garcia is right on some points, but wrong on others (more often he comes across as a Hal-basher).
Sure, there's a whole generation of kids who grew up with John as their Green Lantern--but there was a generation of kids before that who grew up with Kyle, and a generation before that with Hal (we can go even further back with Alan). Everyone has their favorite Lantern that they want to see more of.
We'll probably never know the real motivation behind DC's initial decision to kill off John--it might have been to ultimately bring him back in big way later or it might have been because they thought there were too many Earth Lanterns and someone had to go.
Prior to Joshua Hale Fialkov walking off as writer, it did seem that the plan was to split Hal, Guy, John, and Kyle into their own separate books with John becoming the star of Green Lantern Corps
. Personally, I hope that is still the plan as it really would allow John to take center stage there and move the character in a new direction perhaps.