Just to expand on what a couple people have already said: I don't read this article as suggesting that people ride motorcycles on backcountry hiking trails. The article seems to be more about riding on things like forest service roads, fire roads, jeep trails, etc., which are used to _access_ the backcountry. These are vehicle routes, where it's common to see trucks and 4x4s used as approach vehicles. For the most part, they are not places you would hike (unless your truck broke down). I don't see it as destructive or inconsiderate to ride a motorcycle on these routes, any more than it is to drive a truck on them. As the owner of an F800GS (same bike as in the article), this type of use is exactly why I bought the bike: so I could enjoy riding, instead of driving, to destinations where I can then hike or climb.
The article also is not about OHV areas where concentrated use by dirt bikes, ATVs, etc. has destroyed the environment and rendered the area incompatible with other uses such as hiking. These tend to be destinations for OHV users, not access routes. (I am not going to argue about whether such areas should even exist.)
There are some undeveloped areas (i.e., no roads) where motorized vehicles are allowed and where people ride motorcycles (and ATVs, 4x4s, etc.) off established routes and pretty much go where they want. Certain high desert areas on BLM lands come to mind. I think this type of use has the potential to be very destructive, and to conflict with other, "lower impact" uses such as backpacking and camping. Thankfully it is either not feasible, or not permitted, to ride a motorcycle into most of the places I enjoy visiting. But in some areas that is not true. Personally, I would not ride into these areas even if I could. I know some people feel differently, and to me that is where the real conflict exists.