I don't know of any legally changed. I do know it really sucks when good single track is messed up because people make it wider. Same as stacking rocks on rockcrawling trails and not removing them. Once a trail is 50" might as well let all sxs on it.
How was it up there this weekend? You have some trails in mind regarding widening?
The only trails that I'm aware of that have been widened are some trail out on the Piaute trail system. They did so to make the #1 loop accessible to 60" rides. From talking to the guy it took a bit of effort but it was well worth it for the communities surrounding it.
Not rocket science...change the laws
Some of what I have read is it's not a law thing it's a forest thing and The Forest service can change them but it is a long road to get them done .