You view them as negative because you're only thinking about how it affects you.
There are clear benefits to banning diesel engines in freshwater. That's why so many places are doing it. Lots of people support these measures because it's a very clear benefit.
If a business can't afford to operate without being subsidized by the environment, they shouldn't be allowed to operate. When you use those diesel engines, you're taking out a loan using the environment. That loan needs to be repaid, and it gets repaid in the from of destruction rebuild costs. So when you complain about how "it would cost blah blah to do this safely", what you're really saying is "I want to destroy the environment for some cheap fun" which is deeply, deeply selfish. When you hear the total cost of disasters, think about it in the form of debt being repaid. That $1 billion because of so and so fire, that's the environment coming to collect the debt we racked up because we wanted cheap stuff and recreation.
Remember, your freedom ends where mine begins.