Ratings are recommendations not rules.
Brian, to answer your question. If you were to run a trail where you didn't meet the trail ratings/recommendations and you cause a problem as a result, you should be penalized for doing so.
I big guy may have to sit out a trail just like a little guy will... but we're talking about a vehicle that is simply not suitable for the trail.
Turn this around. If you have 4 guys on your run, well equipped, 40" tires, dual lockers, winches and a single smaller vehicle tagging along. Let's say he's running 33s, open with maybe a winch and a long bed Toyota pickup, oh yeah, and it's JANUARY! Should the smaller vehicle skip out on that run? You bet they should.
I think you misundertand the intent of the system, it's to let people know what they're getting into and what type of vehicle MINIMUMs are required. It's only the idiots who are going to then intentionally take vehicles into trails where they simply don't belong when they are informed about what the trail is like.
There were a couple of issues last year that support these changes. We all recall the group of underprepared vehicles that got on the busy because they really didn't know better (and let's leave it at that) and created a vehicle rescue fiasco of sorts. Proper trail ratings, vehicle recommendations and markings could have prevented this. Conversely there was the second incident of the guy in the full size that basically beat his rig apart and created another vehicle rescue fiasco. Rumor has it he's coming back with a full size blazer to beat his way through again because the "BUSY" beat him. Without a method of enforcement how do we stop him from doing this again? We STILL have the Cherokee up there because we can't get it out.
I know this story very well. I was there for that. Made for a very long night. We warned all of them about the trail and they still followed along.
All the rigs that helped getting them out had damage.