I agree that there could be tremendous downsides, but at the same time I wouldn't want to reach for any type of safety gear and not have it.
What if it's not even "real pirates" but rather a haphazard raid by what are obviously hostile teenage boys from a nearby village operating a raft with a single outboard motor armed with only machetes ? These kids couldn't afford a gun and this could happen anywhere where there's poverty not just in areas known for piracy
Another scenario, what about the stranded boat that looks like it's stuck on a sand bar relatively close to port and is begging for a tow. There could be a pretty girl on board. It could be an opportunist type situation where they really did just need a tow, but when they sense you're unarmed they might try to commandeer your craft since maybe they have warrants, or a shaky visa situation inland or whatever.