Which rather depends on what the game is to be balanced around.
Degree of inclusivity has major balance implications, irrespective of what the game is supposedly balanced around. Other people and the manner in which they may, or must, be encountered is going to be the overriding factor in the difficulty of all kinds of interactions, direct and abstract, in most any multiplayer game.
Player activity is the only activity as far as the BGS or PP is concerned. Without CMDR influence, those things either don't move, or settle into a static baseline state. Difficulty is all about who is engaging with those mechanisms and the specifics of the obstacles faced change heavily if one can instance with one's opponents.
"Well the need for traders to be protected is there"
Getting a group together is hard to do and probably impossible for some, and I believe that the game works against effective merchants and escorts travelling together. IIRC a merchant can be attacked and destroyed a lot of the time before the escorts arrive. If they do arrive, it is easy for the raider to get away. Flying as escort would be a grind and achieve little.
If a group does manage to travel together, the raider can seek weaker prey. Or round up a couple of like minded CMDRs and overwhelm the escorts, or at least enough to kill the merchant.
Due to engagement ranges and other factors, gameplay isn't suited to passive defenders.
Proactive defense works just fine. Even bad pilots can get in fast ships with interdictors, tie up an entire wing each, and escape every single time (though before Engineers there was at least some risk, if one got
complacent).
The problem is that there is little to incentivize the use of escorts, no matter how effective escorting is. A merchant can almost always get through with competent support, but it's usually more advantageous, for any goal beyond combat for it's own sake, to just bring more merchants, even if some of them get popped some of the time.
Then why are they complaining there are no folks to fight?
Who is they?
Despite the experience being severely degraded from it's peak, I can still find plenty of people in Open, if I go looking for them. Usually can't find much reason to fight them though. That's what's missing; incentives and rationales that should logically be there, but aren't. Random gank attempts and duels might be enough for some, but for me even self-defense has become tiresome due to the lack of urgency and inevitability of escape in virtually all encounters, not to mention the negligible consequences of failure. I mean, it's still more engaging that CQC, but it could be so much better.