There needs to be a physical barrier at the trailheads i.e. caution tape, chain, gate, etc. Common sense isn't common not to mention individuals will all have a different idea of what actually is "too wet." I don't see how there can be consequences for for an action when there is no official declaration that that action was prohibited. Will a chain across the trailhead stop every asshat? No, but I would think it will stop most which would drastically reduce the trail damage. .
I get that bikes damage trails. There is no arguing that. But bikes are by no means the only thing damaging these trails. I have ridden 6 Mile during a freeze and there were plenty of frozen boot tracks, etc. Let's not get started on all the dogs off leash. The reality is that none of the rules are followed and that transcends the different user groups.
I get that there have been budget cuts. I am sure the individual park rangers care a lot but the bottom line is that the State of New Jersey doesn't care enough about the parks to invest enough money to properly maintain and police them.
To be clear I don't ride mud. I don't condone it at all and I am not defending those who do. I don't think anyone reading this is a guilty party. That's the problem.