I think one of the reasons why I wouldn't want Robert's Rebellion being brought to life is because of how mystified everything is.
I don't want Rhaegar, Aerys, Arthur Dayne, etc. get a face or a voice. They should remain memories, and be portrayed as such. Everyone who was involved with these characters remembers them differently, and you get very unique portrayals depending on whom you ask.
That's what makes them so special. We hear so much about their legacy, and how their actions started the ball rolling with the events we've been reading about, but we never see them. We never hear them. We don't know how they move, behave, talk, think. What their plans and motives truly were.
I do want to find out what exactly happened during the rebellion. But I want to know it through means other than shattering this veil of mythology and mystery around these long dead characters.
Call me weird, but I just feel like making a spin-off show or even have GRRM write a prequel to AGoT would be a disservice to the SoIaF series. It would smash the romanticism about it.
Dammit George, where's my Howland Reed.