Absolutely!!! Mountain biking is becoming extinct like hunting is. The push is to keep people from pedaling in the backcountry and instead dumping their cars and pedaling in the city on streets because this is "greener" to do so.Most of the issues I have with this is: The area has been open to mountain bikes and now because the place turned to wilderness or proposed wilderness in some areas, I can not peddle there anymore. The example I stated before, are just that. They where legal to peddle and now they are not. It is just no fun to lose access to some of your prized trails, that you have rode for decades. The great burn is a classic case. It is remote, it does not see a lot of people and it was a good place to challenge yourself.
As far as trail erosion, as has been stated before, horses do way more than mtn bikes.
One of the reasons for the push to allow mountain bikes into wilderness, is what I have stated before. Lost access to trails. Not all wilderness areas will lend them selves to bicycles, but some will. People need remote places to push themselves and see what they are made of. They want to pull the 30 mile ride with 6000 feet of vertical elevation in a day. mile to sheep in the lionhead area is a good example. I Never saw a single person. But when the fs management plan comes up for renewal, I am sure mountain bikers will lose that. Like I said, it is just a big bummer to lose trail access, just because some one does not like a clean, quiet activity that does not match there personal beliefs.
Personally, we need another designation besides wilderness. One that protects but allows use.