Exactly. I dont know where people are getting the idea that signs would have prevented this- there are signs. When this incident happened, the sea was absolutely freezing cold, dark, rough, and choppy as hell. The weather was cold and it would have been dark because it was prior to sunrise between 4-5am, so not light.
Brighton beach down near the pier area is not pleasant at this time of year at that time of day. This isnt the gentle lapping waves of a balmy, warm, crystal clear Caribbean sea we are talking about here. Its Brighton.
The beach here is extremely painful to walk on without shoes, it really bloody hurts your feet. The sea at this time would have been rough, choppy, dark and freezing cold. Its not remotely inviting at that time of day/year and so sadly, I suspect alcohol was involved because this isnt a nice place you'd choose to go "for a paddle" at that time in the am and its not something you'd consider when sober and in a logical state of mind. There's a reason why that area was deserted when this happened and there were no witnesses.
Humans are very bad at emotionally feeling danger when nothing bad has happened yet, everyone else seems relaxed, or the activity feels temporary and low-stakes (“just for a second”). This is why people often do risky things on holiday that they would never, ever, do when at home - because their perception of risk is lowered.
Signs work best when someone is already in a cautious, sober mindset. They work less well when someone thinks: “We’re only going near the edge for a second" and they are intoxicated and their inhibitions lowered.
So, whilst coastal safety measures are always worth discussing, there probably isn’t a simple “if only there had been one more sign” explanation here.
If anything, I think the best way to get people to connect to danger on an emotional level where they are most likely to remember it, is more likely to be achieved from those horrifying public information adverts from the 70s/80s. Those things have been burned into my brain because they were scary as hell and worked far better on an emotional level than a sign I paid no attention to.