Jez, I agree! I am a true Chipko when it comes to riding, ride light, leave no trace, enjoy the world around you, stay fit and have fun. That is the whole ethos I espouse with mountain biking.
I am not a big fan of the whole ramp riding trail building freeriding bmx/skater refugee dope smoking litter dropping 8" of travel riding thing.
In my humble opinion the sport has changed so dramaticly in the last ten years that what I do has little in common with 'mountain biking' as we knew it. The sport has changed and I haven't, that is why I ride retro and why I feel that retro cannot be defined by years.