When we think of the desert, we think of a sandy, waterless environment where the sun blazes without mercy. We think of hardy creatures like camels, coyotes and buzzards. What we fail to realize is that deserts have complicated and very fragile ecosystems.
And right now, the American desert is being threatened by off-roaders. Many off-roaders have taken to the desert, presumably due to the lack of roads there. These roadless road-warriors tear around in their fancy, little go-faster machines, doing tricks and probably some wheelies.
Off-road vehicles are wasteful on a philosophical level. Any machine that has no function outside of entertainment is superfluous. An all-terrain motorbike has no purpose but entertainment. (You could buy a more efficient motorbike for transportation.) Therefore, an off-road bike is wasteful.
I'm not going to be a wet blanket and say that people shouldn't off-road, but maybe they shouldn't. OK. I'm a wet blanket. But look. When someone takes their sweet motorbike out on the dunes, they kick up dust. The dust goes into the air and lands in the mountains. The dust causes the snow to melt. Eventually, the snow will begin to melt during times when it should not be melting. Farmers do not get the water that they need for their crops during the times that they need it. Climatologists are still debating the long-term effects of this mountain dusting. Some fear drought. Others fear flooding followed by drought.
Off-roading also interferes with the desert wildlife, and spectators tend to leave behind litter. The Peirson's milk-vetch, a flowering plant native to the Algodones Dunes, has become endangered due to human over-involvement in the desert.
I would love to come out and say that off-roading is totally sweet and harmless to the environment and that all the nay-sayers are just jealous because they don't have an awesome bike. I can't though. Desert off-roading is probably bad for the environment.