First, it requires that FTL ships be cheap enough that criminals can acquire them. This is another area in which the analogy between the age of sail and the space age breaks down. Sailing ships were skill-intensive but materially cheap. You had to have people with the right skills, but once you did all you needed was wood, rope, and cloth. But spacecraft are going to follow a post-industrial revolution paradigm of being materially expensive as well as skill-intensive. They are likely to require sophisticated, precision-manufactured components and expensive fuels like helium 3, fissionables, or antimatter. Imagine Captain Jack Sparrow commanding a nuclear-powered aircraft carrier and you’ll get an idea of the kind of difference we’re talking about.
If technological trends continue, the degree of technology available to the average citizen and the average criminal will continue to increase. As an individual, I have access to more media distribution than Queen Elizabeth could even imagine. As an individual, I can build a device like a CNC machine or a 3D printer from off the shelf parts.
Skillfully crafted wood, rope, and cloth would seem like miracle items to someone from the stone age. A CNC laser cutter would represent miraculous technological savvy and princely embodied wealth to someone from the 1400's. The equivalent to an Orion ship might well be within the rech of rogue elements of the late 21st century.
That said, space piracy probably won't happen, or at least won't resemble piracy from old movies in the least, but the technology being out of reach won't be the reason why.
Piracy would likely extend solely to the theft of energy resources. Similarly, so would war but on a bigger scale.
Piracy of goods would only extend to things not easily replicable by the present technology, or not easily replicable on many colonies. Even then, you're looking more at the theft of raw materials or for material value. Piracy would likely resemble robbing armoured vans today than any kind of piracy we've seen before, but they'd likely be trying to get precious metals or power like uranium.
Endless wars over oil, rare earth metals in Africa and the ever increasing price of iron ore would tend to indicate you might be wrong about that.
Just because a single 3D printer won't use much won't magically make resource constraints disappear.
Carbon, silicone and iron are easy to come by in space. Actually, given that olivine may be a common material in asteroids you're looking at abundant magnesium, iron, silicone and oxygen right there. However things like rare earth metals may be less easy to come by and if 3D printing jumps to molecular printing, then there'll be ships carrying pure metals as goods. Consider Neodymium cost averages $350/kg, a ship hauling it out to Neptune will be worth a lot of money stolen. Especially when the pirates would be selling for <$300/kg.
If piracy happens over raw materials, eventually so will war even if it's just to stop the pirates. However there'll be asteroids found with thousands of tonnes of easily mineable rare metals, and then we'll see space battles.
Others will value their freedom more and try to get by with less, and will avoid such political and literal hot spots. The vastness of space will be their most valuable resource. They may well be the final nomads and the last vestiges of humanity.
91 regularly occurring natural elements is a much shorter order than tens of thousands of common molecules. Considering there are over forty simple hydrocarbons and molecular printers start looking bulky, granted you might only ever use a maximum of 5 hydrocarbons, but that day you need a 6th you'll be cursing your shitty base model printer.