The bridge was built when there was heavy commercial traffic on the river. It wasn't designed to opened every twenty minutes for pleasure craft. Operating a movable span involves a lot of work and man power every time an opening occurs. It isn't just pressing a button.
If the bridge were to fail in a raised position, the railroad may be liable to its customers for delayed shipments. It is probably a situation where any fines or lawsuits are outweighed by operating costs or incidental penalties the carrier may incur. They are in the business to haul freight, not placate pleasure boaters.
The bridge was there before the boat rental companies and excursion boats arrived on the scene. The boat company owners made a poor choice of locating their businesses with out doing their homework beforehand.
I am surprised to see how many of the responders on this thread are against the railroad. It is a debatable issue, but the negative view of the railroad puzzles me. If your new Lionel locomotive was in a UPS container on a train delayed for a bridge opening and arrived a day late, you probably would not be happy.
Finally, being a career railroad employee, as well as a model railroader, I can see the question Is important to a few people ut not the railroad. But in reality, it is a non issue that seems to have risen from the newsroom floor on a slow day...
The answer to your question is that rivers and other navigable waterways are not owned by the railroad and as a result watercraft have a right to navigate that waterway. Those rules were not created for commercial boat traffic only, they weren't created for commerce, they were created for anyone using the waterway, boating on them. It doesn't matter that back in the days of the NYC this route was used mostly by commercial shipping (and it would be interesting to see if back when the NYC ran this, if they kept the bridge up or down), the fact is that the Cuyahoga river (thankfully) is now clean enough along with lake Erie to allow it to be used by all kinds of craft, commercial and non commercial.
And if this line is that busy that they can't afford to have the bridge stay open unless needed, then the railroad should be seriously thinking about how to either reconfigure the route to be able to cross the river without affecting river traffic or to replace the bridge. Among other things, the real risk with that bridge isn't that opening and closing a bridge is difficult, the real risk is that bridge is ancient, probably built in the earlier part of the 20th century and as such is probably prone to failure, when they continue to use infrastructure that was built for another time (as the poster noted, when the river was mostly commercial traffic) that is on the railroad for taking the cheap way out. Looking at the pictures of that bridge, I see another problem, given the kind of flooding we are seeing routinely these days, that bridge is a disaster waiting to happen for another reasons, it is so low to the water that it is prone to being flooded out, and also in winter could end up getting destroyed by ice floes if the weather goes into a deep freeze.
The worse part seems to be that there was a workable flow to the way it once operated and the NS didn't care. Allowing the bridge tender to decide when the bridge needed to be lowered, rather than having to wait for a dispatcher a thousand miles away to decide, made sense. The bridge tender likely will have access to some sort of information on trains coming to the bridge, so they will know if they need to lower it or not, and it doesn't take 3 hours to lower a lift bridge like that. Likely, too, a lot of the trains running over that bridge probably happen at night, when recreational traffic and the like is at a minimum, likely peak times for recreational traffic are weekends in summer, so it isn't like they can't work out a compromise where the bridge is up by default during peak times for river traffic and down/on demand others. What it sounds to me like is the NS is assuming that mere pleasure boaters and other users don't matter, and they do, the NS doesn't own the river, and to be blunt their business interests in trying to operate the bridge as cheaply as possible to them or only with their interests in mind legally and otherwise is just plain arrogance, the guys who run marinas and tour boats and dinner cruises and the like are business people, too, they rely on the river for their livelihood, and the people who boat on the river and lake likewise have a right to enjoy it, too.
The anger being thrown at the railroad is that in the name of squeezing every cent out of their business, they are acting like 19th century robber barons, not responsible corporate neighbors.