I think conventionally the verb is "to steelman" with the intended contrast being to a strawman, an intentionally weak argument by analogy to how straw isn't strong but steel is. I understood what you meant by "strongman" but I think that "steelman" is better here.
There is indeed a good reason regulators aren't just obliged to institute all recommendations - that would be a lot of new rules. The only accident report I remember reading with zero recommendations was a MAIB (Maritime accidents) report here which concluded that a crew member of a fishing boat has died at sea after their vessel capsized because they both they and the skipper (who survived) were on heroin, the rationale for not recommending anything was that heroin is already illegal, operating a fishing boat while on heroin is already illegal, and it's also obviously a bad idea, so, there's nothing to recommend. "Don't do that".
Cost is rarely very persuasive to me, because it's very difficult to correctly estimate what it will actually cost to change something once you decided it's required - based on current reality where it is not. Mass production and clever cost reductions resulting from the normal commercial pressures tend to drive down costs when we require something but not before (and often not after we cease to require it either)
It's also difficult to anticipate all benefits from a good change without trying it. Lobbyists against a regulation will often try hard not to imagine benefits after all they're fighting not to be regulated. But once it's in action, it may be obvious to everyone that this was just a better idea and absurd it wasn't always the case.
Remember when you were allowed to smoke cigarettes on aeroplanes? That seems crazy, but at the time it was normal and I'm sure carriers insisted that not being allowed to do this would cost them money - and perhaps for a short while it did.