It's not always a kid. In fact, the rebel spy has been an adult probably half the times that I've been on it. I've been the rebel spy, and so has my bf. I think it all depends on the CM, since they can agree with the random photo or choose another. Some may look for kids, and some may look for adults making unintentionally silly faces. I think it's fun and makes the whole experience more interactive.
I never really liked 1.0. I only rode it once as a kid, and there was vomit on the seat in front of me. They didn't clean it very well (or at all?) and just covered it with a tarp. It was so gross that I didn't go on the ride until I was an adult, and that was only if I was leaving Space Mountain at 11:57pm and there was time for just one more ride. There was never a line at that time. I guess I was disappointed that we never made it to Endor, or anywhere else really.
In contrast, 2.0 is great! Although, it's such a waste of time if it's the pod race and the big city (Corcasan???). Hoth and Naboo are the best.