You are correct in that GP's are not motocross. Although some motocross is included in the track layout. Like Hershey, in MX it usually takes me a couple laps to get my body to adjust up to racing speed. We also know, that part of the reason GP's are gaining in popularity are due to shortcomings and issues in MX racing, race "track time" included.
I have never been a fan of woods racing, but I do love a long track, and a track that is designed for the average rider like me. We all want a track that we can compete on, but I still like to be challenged and stretched. I like changes, and a track that flows, but then sections that impede flow and slow you down. I love the GP's in that I often can go as fast I as dare to go, and charge like hell for as many laps as I can squeeze in, especially if I flop somewhere and have to play catch up. They could take out all of the tree's, and I'd be happy, as long as we still had a minimum of a 5-7 minute lap time. And longer is better. Or give me a 2-3 minute lap time, but 30 minutes.
I guess what I'm saying is that the motocross side of our sport needs to look closer at the positive things that GP racing gives us, and what the riders really see in GP racing. Especially the schedule format in that you almost always know exactly when you are racing, and when it's over. (Another note, is that in GP racing there is no warm up or practice laps. We just throw the flag and go!)