I don't think it is any different than building an MX track. Don't know if goes too far, nice to see guys keep on pushing the envelope...just look at how far enduro racing as gone...and keeps on going. Pretty dang amazing what some of those guys can do.
I have ridden some of that Shoots and Ladders crap at the North Shore and Whistler British Columbia, it is pretty fun. Sure does make your ass pucker and your balls shrink.
http://www.youtube.com/watch?v=t2DcwDQxUKQ
As for trail access, would be nice if everyone learned to share. I see the moto guys are suing the Forest Service in Colorado over only motorized being kicked out. I say it is about time, I have been saying that for years...if the selfish mountain bikers and hikers refuse to share, kick those SOB's out as well. Pretty dang ridiculous that we are fighting over how one another recreates...when there are far greater problems in this World to tackle.
I dunno about you guys I enjoy it all, moto, bicycle, hiking...heck might even catch me on a horse too.