I'm afraid you still don't get it and the traders you refer to neither. In a galaxy of such vastness you just can't simply ensure balance by numbers because most traders that are able to put one and one together would avoid the main traffic routes. And here is where the piracy will happen: Good pirates will concentrate on the well known "efficient" trade lines. That is where the whole beauty of Elite shines: All the greedy folks who are coming from other modern MMOs with the attitude where only efficiency counts will be the preferred prey of these pirates. In other words, they get what they deserve or get what they choose: risk vs reward.
The only problematic part in this wonderful concept is the solo mode. My solution to this would be to track the actual piracy activities in open (by simple statistics) and translate these to solo mode, where the most efficient (and hopefully pirates infested!) routes will be synchronously filled with comparably dangerous NPC pirates. The tricky part for the devs will be to find a balance between PC and NPC pirates. If better AI won't work or being impossible then through harder weapons and/or higher level ships or even by sheer numbers of NPC pirates. ***
That would be my preferred way to a decent risk vs reward concept without the possibility of a risk free chicken out to solo. This even could revalue the solo mode as no one could seriously call out solo as the <carry-my-beer-mode> anymore.
*** This process could even be automated. Here's a simplified example to illustrate the idea:
Let's assume there are 10 different NPC ships on a difficulty scale of 1 to 10 from easy to hard. Then let us take a certain system were PC-piracy occurred and acceded a certain threshold, let's say 5 times in 3 days. The server could then generate a higher class of NPC-pirates on the solo version of this system and track the result. If after 3 days the sum of killed trader ships are still below that of the system in open (and assuming the statistics haven't changed here, just to keep it simple for our example) the next generation of NPC pirates would be generated. If the system was set on difficulty 3 before it's being set to 4 now and so on, until the system in solo shows the same trader killing rate than its double in open.
The reason not to trade in open is because it is no fun to get randomly blown up by an OP opponent (be it a PC or NPC, who cares) while in a ship like the T6 which can't defend itself. It's boring, you lose too much. It doesn't add any fun factor at all. The risk is simply too high for the reward and hence people don't want to subject themselves to it.
Your solution only pushes the same amounts of "deaths" which occurs in open to solo (deaths must surely count as murder rather than piracy though, but never mind). You add risk to traders while pirates still suffer from no risk what so ever.
Personally I don't like to think of things in terms as risk vs reward, it's not necessary. I like to think of things in challenging gameplay and cooperation = reward. There doesn't even need to be a lot of risk involved, just make it FUN for all parties, including the ones being pirated in a way that rewards more you the better you play. How about instead of adding more risk, you reduce the financial damage caused by PVP deaths to next to nothing instead. I'd like that a whole lot more than additional reward when I'm trading (and I do a bit of everything, not just trading). It would encourage people to PVP too because they have less to lose.
Your suggestion to beef up the NPC's is hard to argue with though. They need some more challenge to them - both pirates and security.
